I changed my battery and it’s not showing the battery health what would I do to that ??

You changed the battery yourself?

That would explain it.

Apple does not sell iPhone parts, including batteries. If it was replaced by you personally or by an unauthorized shop, you did not install a genuine new Apple Battery.

In addition, Apple won't touch that device now that it's been tampered with.

Return it to the repair shop who installed the replacement battery.