I changed the battery, it does not show the health percentage of the battery

If you replaced the battery yourself, you will not see that information. The replacement needs to be done by Apple or an authorized repair shop in order for that feature to show.

~Lyssa

If you installed the battery, or a non-authorized shop did, a genuine Apple battery was not installed.

Now, you won't see any information about Battery Health.....and.....because service was performed by an unauthorized person, Apple will refuse to even look at the phone in the future if service is required.