Can you describe exactly how you are increasing font size?Increasing font size takes up only a tiny, tiny fraction of the "real estate".
I have a 4k 27" monitor that I use in portrait mode for charts. I use Windows 10 Display settings to change "Scale and layout" to 125%. This makes everything larger, not just the fonts, so I do lose some screen real estate. I'd love to get more screen real estate while keeping fonts somewhat legible.