you will require a higher resolution monitor to achieve more screen real estate assuming you operate with the same pixels per inch (not Hi DPI scaled). if you increase resolution and keep the same size monitor and don’t DPI scale then your text will be smaller.
So to get more real estate and keep thing readable, you need a higher resolution, larger monitor and to not DPI scale. Easy!
Personally, I prefer multiple monitors. It’s cheaper and easier to manage the window arrangements IMHO. I used to have 6 attached, now I have 3, the kids decided they needed the other four so we all have 3 each!