Minecraft Legends

It order to be able to spawn witches you have to gain their trust first.
After November update you can find witches hut in villages when you starting a new game. I've checked and witches huts don't spawn on existing saves before the update.

Witches Hut is a tall wooden building and there will be a witch nearby. I believe you can find it in any village.
Now you have to wait until piglins will attack a village with a Witches Hut in it. You must not ignore the attack and defend the village. After attack is over you will gain trust of witches along with ability to spawn them. You can spawn witches only using Witches Hut, so go to the building and spawn 50 using . If you don't have enough slots for spawned mobs - you have to get them killed in a battle and then spawn again or build an upgrade for additional slots. There is no way to return witches like other mobs.

Methods with custom game:
Thanks to DaConnDude for checking out Witch Hut Placement parameter!
1. Create Custom Game with parameters:
- Resources -> Starting Resources - Max out or set as much as possible, to have enough resources for everything. You don't have to set Max Resources.
- Player Tools -> Tech Tree -> Unlock All
- Witches and Warriors -> Witch Hut Placement - set to Free Form
2. After you applied settings above press to save and continue.
3. Near the well build 3 or more Improvement: Large Flames of Creation
4. Now build Witches Hut anywhere you want because placement was set to Free Form (witches hut is found in the combat melodies - Thanks Dread Girl)
5. Proceed with spawning 50 witches thanks to previously built Flames of Creation

It order to be able to spawn witches you have to gain their trust first.
After November update you can find witches hut in villages when you starting a new game. I've checked and witches huts don't spawn on existing saves before the update.

Witches Hut is a tall wooden building and there will be a witch nearby. I believe you can find it in any village.
Now you have to wait until piglins will attack a village with a Witches Hut in it. You must not ignore the attack and defend the village. After attack is over you will gain trust of witches along with ability to spawn them. You can spawn witches only using Witches Hut, so go to the building and spawn 50 using . If you don't have enough slots for spawned mobs - you have to get them killed in a battle and then spawn again or build an upgrade for additional slots. There is no way to return witches like other mobs.

Methods with custom game:
Thanks to @DaConnDude for checking out Witch Hut Placement parameter!
1. Create Custom Game with parameters:
- Resources -> Starting Resources - Max out or set as much as possible, to have enough resources for everything. You don't have to set Max Resources.
- Player Tools -> Tech Tree -> Unlock All
- Witches and Warriors -> Witch Hut Placement - set to Free Form
2. After you applied settings above press to save and continue.
3. Near the well build 3 or more Improvement: Large Flames of Creation
4. Now build Witches Hut anywhere you want because placement was set to Free Form
5. Proceed with spawning 50 witches thanks to previously built Flames of Creation