How to add contact to favorites

Mr. Bacon wrote:

I've done it dozens of times but now, when I click on a Contact, there is no "add to favorites" option.

Have you shutdown & restarted the iPhone ie power off/on...

Restart your iPhone - Apple Support

ref: Use Contacts from the Phone app on iPhone - Apple Support

Select a contact, scroll down, then tap Add to Favorites.

the current stable release, including bug fixes iOS 17.6.1

Update your iPhone or iPad - Apple Support

Mr. Bacon wrote:

I've done it dozens of times but now, when I click on a Contact, there is no "add to favorites" option.

Have you tried it the other way? Go to Favorites and tap the "+" in the upper right corner.