How to remove damage immunity?

After you attack a player or mob, they are invincible for around 0.5 seconds, and hits do not register to the mob/player’s health. I am trying to remove this damage immunity so that all hits register to the mob/player’s health for this server I’m working on, so I looked for behavior packs that would do it, however I can only find damage immunity-related content associated with Java edition, which I cannot use. Any ideas?