If a site is not designed for view on a tiny display, you’ll most likely need to be performing a lot of zooming and scrolling.
Think of a web page like a printed newspaper. If you try to view a printed newspaper by folding it up to be the size of a small paperback book, it’s going to be a challenge to read.
That said, may sites have implemented both desktop and mobile views by design (it’s called “Responsive Design”). Most site-browser combinations will pick the best code path for your screen size.
But that doesn’t always work as expected.
Some browsers, such as Privacy Browser, have options to allow you to manually adjust the view to hopefully improve your experience.
Sometimes Privacy Browser works great to improve sites; other times, not so much.
Note that online forums are notoriously bad for this sort of thing because the forum software has to allow postings with unpredictable formatting. When someone formats a post with a dozen wide columns, it’s not easy for the forum software or web browser to accommodate the restrictions of a small screen.