Hi I was wondering if its possible to favorite/heart something by a Tag? or like by Artist

Not by default.
Users sometimes write their favorite searches on their user information, so they can just click on that to look up those tags.
Various apps have been posted, like forum #257629 which claims to have feature to get notified when your chosen tag gets new items.
Or just watch artists on FA instead.

milktruckk said:
Hi I was wondering if its possible to favorite/heart something by a Tag? or like by Artist

Not automatically without writing a script using the api to do it, but on the main posts page you can change the mode (under the search bar) from "view posts" to "add to favourites", then can just click the post thumbnails to add them, which would make it quicker at least.