I have a 27" 4K display that I run at 1440p because 2160p is too small for me to read text easily. I'm on Linux and don't use any scaling. 1440p on a 27" at roughly 3ft viewing distance is slightly better than Retina quality according to this[0] calculator.
Use "large text" setting in accessibility settings (assuming you're using Ubuntu), and zoom in your browser, terminal, and text editor using their own settings. That's what I do. Looks great. Though my monitor is 32".
[0] https://www.designcompaniesranked.com/resources/is-this-reti...