If I clear my gallery data, will I lose all of my albums? My gallery has been taking up a lot of data to the point that I have little data left. If I clear it, will all my albums be deleted?
Data store by the gallery apps are thumbnails it generates to preview the pictures and videos. The Gallery app can be considered as a movie theater where you go to watch a movie (in your case, viewing picture and videos in your phone). If its goes bankrupt (in your case deleting its data), it won't stop you from going to another movie theater.
Furthermore, if you delete the Gallery app's data, next time you opens it, the thumbnails will be recreated. When you navigate inside inside the folder thumbnails, more thumbnails will be recreated to preview their content. That's what increases its size.