HiDPI (High Dots Per Inch) displays, also known by Apple’s “Retina Display” marketing name, are screens with a high resolution in a relatively small format. They are mostly found in high-end laptops and monitors.
update this
~/.Xresources
Xft.dpi: 240
reboot or re-login to system
*240 dpi is suitable for 3840x2160 resolution screen (15.4 inch displays )