I'm using both Enhanced Visuals and Vampirism and was hoping you could disable heartbeat effects for players that are vampires or add a way for me to do so, since vampires don't have a beating heart.

Vampirism:
CurseForge
Modrinth

You could disable the heartbeat for everyone. There is unfortunately no way to exclude it for certain players. I'm not sure if this is even desirable, because you might expect for the heart beat to appear when having low health despite being a vampire.

If you really think this is a good idea, I could get in contact with the author of Vampirism and ask if there is an easy way to tell whether a player is actually a vampire.

Also sorry for responding late.

While I think it's a good idea, I also understand it's a niche request. So it may be best if you wait till more people make the same request or you just have spare time to work on something like this.

Also, the late response is no problem. I'm guilty of doing the same thing a lot. Sometimes life just happens.