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.

Steps to reproduce

1. Wear a full set of unenchanted armor.
2. Place TNT next to you and note your coordinate.
3. Ignite the TNT.
4. Note the coordinate where you land.
5. Enchant your armor with lots of blast protection, heal, and repeat steps 1-4.

Expected result

After enchanting your armor with blast protection you are knocked back a shorter distance by the explosion.

Actual result

You are knocked back the same distance from the explosion with or without blast protection on your armor.