Changing screen mode

I used to own an iPhone 7. There was an icon when you scrolled up with stuff like a flashlight, etc. one was an icon for enabling horizontal mode. On this phone, I can’t find an icon or switch. Oh yes, when I wish to read a book or on my safari, I can only do vertical. What am I missing here pls? Thanks

It works only with videos, such as utube. When I try it for reading text, it remains vertical.