Can I use a Mac Mini M1 with a Dell u4021qw monitor?

My computer is a Mac mini with M1 chip. I want to buy the Dell u4021qw monitor, but I have a concern: Does the computer actually work with this monitor (especially: does hidpi work? Does the font become unclear when using hidpi)?

The 2020 M1 Mini supports up to 4096 by 2160 pixels at 60Hz (HDMI); and up to 6016 by 3384 pixels at 60 Hz (Thunderbolt).

HiDPI simply uses the existing resolution, but scales things to a larger size. MacOS can usually scale any display.

Your DELL monitor is 5120 x 2160, so will work over Thunderbolt/DisplayPort. MacOS will scale the display to a Retina equivalent of 2560 x 1080.

The sharpness of the image, or of font display, is usually related to the pixel density. Your 40 inch display is 140 pixels per inch, so won't be as sharp as a MacBook Pro's 227 ppi, but is sharper than the non-Retina Apple Thunderbolt Display (109 ppi, 27", 2560 x 1080).