According to the wiki, the blast protection enchantment reduces knockback from explosions. This is apparently a well-known behavior in Java Edition judging from
MC-103709 and MC-194735. However, in Bedrock Edition blast protection has no effect on knockback from explosions.
- Wear a full set of unenchanted armor.
- Place TNT next to you and note your coordinate.
- Ignite the TNT.
- Note the coordinate where you land.
- Enchant your armor with lots of blast protection, heal, and repeat steps 1-4.
After enchanting your armor with blast protection you are knocked back a shorter distance by the explosion.
You are knocked back the same distance from the explosion with or without blast protection on your armor.