My iPhone 8 battery health percentage is at 80%. Should I change it?

Yes absolutely have the battery replaced. You have a poor battery condition which cannot provide sufficient power for peak performance. If your battery's Maximum Capacity shows a value of 80% or less, then it has gone through its lifecycle and therefore should be replaced, according to Apple.

Axel F.

Yes, 80% is when you should consider replacing the battery. The details about how to have Apple do it (usually while you wait) are in this link→iPhone Battery Replacement - Official Apple Support

You are welcome.

Axel F.