Photos and slideshows on iPad

Does anyone know how to stop photos and slideshows from zooming in so they fit your whole screen? This used to happen to me quite a while ago but it went away and photos and slideshows would show the whole picture but now i can’t even zoom out. It’s been really annoying me and I was wondering if there’s anything I can do so I can watch TikTok without having to rotate my screen every time so I can see full pictures