Again, you can't get damaged by shooting an armor stand with a full suit of armor enchanted with thorns.
- Enchant a full suit of any armor with thorns
- Put it on an armor stand
- Get a bow, crossbow and arrows and go to survival
- Shoot it
You don't get damaged by the thorns, since projectiles get also affected by thorns.
You should get damaged, just like a skeleton shooting you with a full suit of netherite armor with thorns.