I don't use Facebook. (I can't. I managed to get suspended a few minutes after I signed up, despite never having made a single post!).
However a bit of Googling suggests that
(a) you can't turn off 'suggested for you' within Facebook's own settings ; but
(b) you can install a free browser extension that gives you much more control over how Facebook works for you. It's recommended on countless reliable websites (such as that of PC World magazine) and works with all Chromium-based browsers (such as the latest version of Edge, Chrome, Slimjet, etc) and Netscape-based browsers (such as Firefox):
https://www.fbpurity.com/
Once you've installed it, you should be able to achieve what you're seeking to do.