start the selection process by holding on a user avatar (in a view with posts or profiles). then you should be able to tap the avatars of anyone else (also ui to exit selection mode, and toggle to select on scroll) and press a button to open a menu where you can like, repost, save, follow, mute, block, add to list, or hide (and for own: mute, delete, edit interaction settings)
for posts, actions can be commited against post or account. for accounts, only the accounts.
(my skeet about this: https://witchsky.app/profile/xan.lol/post/3mkpxtr6mtc2g)