
You can change the design of some of the mobs by using a name tag on it.
Rename your name tag with an anvil and use it on the specific mob.

If you want to change name tag texture, you will need Optifine or alternative mod that has CIT feature.
Example of correct usage:if you want to use “Maid” variant
eeeee ×
ma_id ×
Maid ✓
maid ✓
all_you_need_is_Maid ✓
It will work as long as it has the word in it.

From 1.21.5, name tag texture changing doesn’t need CIT feature.
Example of correct usage: if you want to use “Maid” variant: