Thanks, but I believe @Falco may have been referring to Admin > Customize > Text. For example I can find this piece:
js.user.change_avatar.title
and I expected there would also be a higher-level template that defines the entire user’s preference page and contains that piece. By removing the avatar section from that template, one could prevent users from changing their avatar. (Or their full name, which is what I want to do.)
But I still can’t find the template that defines the users preference page.