Invitation to the Spirit Festival

[npc=126332] offers the quest inside the Embassy. It showed in Stormwind as a purple triangle on the map.

This is the questline for the Pandaren Heritage armor sets. As for now (TWW), you must be on your [race=25] and be level 50.
Horde starts at Ji Firepaw: Invitation to the Spirit Festival
Alliance starts at Aysa Cloudsinger: Invitation to the Spirit Festival
I'm posting the Horde version but they appear to be the same quests.

1. 
   
2. Invitation to the Spirit Festival - meet [npc=229266] at the marked area
3. 
   
4. [quest=84452] - take the [npc=237286] and meet [npc=229339]
5. 
   
6. To Morning Breeze - travel to Morning Breeze.
   - [quest=84459] - search 8 Wooden Barrels
   - [quest=84458] - find the 3 clues
   - Red Hand or Herring? - confront the hozen chieftain and then find the fireworks. Go to the next quest area:
   [quest=84453] - travel to Dai-Lo
   - [quest=84454] - kill enemies or click things to fill the bar
   - [quest=84455] - find [npc=229269] inside the cave. Run over the dust to reveal [npc=229487] and kill it. Entrance the the cave should be marked but in case it's not: /way 71.56 70.48 Cave
   - Brew You One Better - click the drinks on the table and serve them to the pandarens near you
7. 
   
8. [quest=84461] - tavel back to the temple
   
9. Patterns in Static - run through the blue bubbles around the temple (mounted or not). Go to the marked area and click extra button [spell=463163]
10. 
    
11. [quest=84463] - kill [npc=229411]
12. 
    
13. [quest=84464] - talk to [npc=231214] and follow its clouds. Talk to [npc=229460] and then to [npc=231286] inside the fire
14. 
    
15. Of Water and Blood - (run a bit so you can mount up) then kill enemies and collect flowers. Place them at the memorials
16. 
    
17. Thousands of Years Ago... - talk to Li-Li and then fly to the nothern part of the isle. Click the barrel to start the fest
18. 
    
19. This Was Home - enjoy the fest and talk to the NPCs ([npc=231403]s start small duels) to fill the bar
20. 
    
21. A New Tradition - meet [npc=231913]. You will get two sets (depending on your faction) and also receive the toy [item=242520]. I assume that the corresponding set is also unlocked for the other faction.
22. 
    
    Questline took about 25 minutes.
    
    Pandaren Heritage Normal: [outfit=625674]
    Pandaren Heritage Horde/Red: [outfit=625681]
    Pandaren Heritage Alliance/Blue: [outfit=625682]

Heritage armor:
With The War Within, you can level up as you want, including using a character boost or a race-change and gain the achievement (like Heritage of the Lightforged). Once earned, you can use this transmog on every alt of that race. Some races get more than one set.
Older/main races may complete a quest chain to get their heritage armor (currently level 50+ and possibly additional requirements, depending on their race).

In case it doesn't pop up on log in, try to visit the Embassy to find the quest giver (Stormwind / Orgrimmar). A relog might also be helpful if you've just leveled up.
Some races need a teleporter near the Embassy to turn in their quests. /way Stormwind 54.4 15.4 Embassy SW /way Orgrimmar 40 76 Embassy OG

Alliance:

1. 
   
2. Draenei (non-lightforged) 1: [outfit=528866] - pick up Magically-Sealed Parcel in Stormwind to start An Artificer's Appeal /way #84 53.2 15.7 Parcel
   Draenei (non-lightforged) 2: [outfit=550826] - you get two helmets for both sets
3. 
   
4. Dwarf: [transmog-set=2897] - Questline starts in Stormwind: Keep Yer Feet On The Ground
5. 
   
6. Dark Iron Dwarf: [transmog-set=2765] - The Anvil-Thane's Designs
7. 
   
8. Gnome: [transmog-set=2995] - Shifting Gears
9. 
   
10. Human 1: [outfit=460885] - An Urgent Matter
    Human 2: [outfit=460884] There are also [item=203176]s as alternatives for the chests, like [outfit=486147]
    Human 3: [outfit=460883]
11. 
    
12. Kul Tiran: [transmog-set=2950] - Heritage of the Kul Tiran
13. 
    
14. Lightforged Draenei: [transmog-set=2780] - Heritage of the Lightforged (use Stormwind teleporter at Embassy)
15. 
    
16. Mechagnome: [transmog-set=11976] - Heritage of the Mechagnome (use Stormwind teleporter at Embassy)
17. 
    
18. Night Elf: [outfit=486135] - The Clarion Call
19. 
    
20. Void Elf: [transmog-set=2782] - Heritage of the Void
21. 
    
22. Worgen: [outfit=233232] - The Shadow of Gilneas
23. 
    

Horde:

1. 
   
2. Blood Elf: [transmog-set=2896] - Questline starts in Orgrimmar: The Pride of the Sin'dorei
3. 
   
4. Goblin: [outfit=529142] + [item=174077] - Old Friends, New Opportunities
5. 
   
6. Highmountain Tauren: [transmog-set=2779] - Heritage of Highmountain
7. 
   
8. Mag'har Orc 1: [transmog-set=2778] - Heritage of the Mag'har
   Mag'har Orc 2: [transmog-set=2777]
   Mag'har Orc 3: [transmog-set=2766]
9. 
   
10. Nightborne: [transmog-set=2781] - Heritage of the Nightborne (use Orgrimmar teleporter at Embassy)
11. 
    
12. Orc 1: [outfit=486143] - A Summon to Orgrimmar
    Orc 2: [outfit=486144]
    Orc 3: [outfit=550827]
13. 
    
14. Tauren: [transmog-set=2952] (the big totem is a cloak: [item=170063]) - When Spirits Whisper
15. 
    
16. Undead: [outfit=486131] (you get two chest styles, [item=210054] (3D_1 and [item=208476] 3D_2) - Unliving Summons
    - your Undead must have completed the Dragonflight Pre-Patch event questline Return to Lordaeron. If you still need to complete it, meet Calia Menethil for Call to Lordaeron
17. 
    
18. Vulpera: [transmog-set=11977] - Heritage of the Vulpera
19. 
    
20. Zandalari Troll: [transmog-set=2951] - Heritage of the Zandalari
21. 
    
22. Troll (Darkspear) 1: [outfit=528663] - Return to the Echo Isles (try to talk to Zi'guma if it didn't pop up)
    Troll (Darkspear) 2: [outfit=550822] + two additional masks: [item=218118] and [item=218119]
    - completing the questline on a Warrior, Death Knight or Hunter ((hotfixed) It will also grant you [item=218105]
23. 
    

Both:

1. 
   
2. Earthen 1: [outfit=550808]
   Earthen 2: [outfit=550805]
   Earthen 3: [outfit=550810]
   To unlock the Earthen, the criterias of the achievement Allied Races: Earthen are required.
   This includes the campaign The War Within and questlines in Isle of Dorn: Before I Depart, Ringing Deeps: Discarded and Broken and Dornogal: How Scandalous!.
3. 
   
4. Pandaren 1: [outfit=625674]
   Pandaren Horde/red: [outfit=625681]
   Pandaren Alliance/blue: [outfit=625682]
   Alliance starts at Aysa Cloudsinger: Invitation to the Spirit Festival, Horde starts at Ji Firepaw: Invitation to the Spirit Festival. You will also receive [item=242520].
   
5. 
   

• 
  
• You can change the previewed race/body by clicking on the arrow below the picture on the armor's page.
• 
  
• "Heritage armor quests for non-Allied Races no longer requires Exalted reputation with their home factions." - https://www.wowhead.com/news/dragonflight-patch-10-1-ptr-development-notes-for-april-4th-class-changes-and-332315
• 
  
• "Using a Character Boost, Race Change, or Faction Change no longer disqualifies the character from doing Heritage Armor quests." - https://www.wowhead.com/news/war-within-pre-patch-hotfixes-for-july-24-2024-hunter-nerfs-345438
•