How do I know HiDPI is enabled? (4K, M1)

[shamole]

Hi,
I just bought a new monitor, LG 27UL650W, is 4k60hz using HDMI to connect it to the Mac mini M1.

When I open Settings - preferences I get this screen, and pressing option + click get me this list of resolutions but I can't see HiDPI. Is it HiDPI already or am I doing something wrong? Should I buy a DP to USBC cable? (I hope not because I need the 2 usbC ports..)

Thank you!

 

[jameson_lewis]

Fire up another Terminal window and afterward reorder the accompanying order:
$ sudo defaults compose/Library/Preferences/com.apple.windowserver.plist DisplayResolutionEnabled - bool valid

Then press Return to execute the order and, in light of the fact that this is a "sudo" order, enter your administrator secret word when provoked.

Then, reboot your Mac and, after logging back in, go to System Preferences and snap on Displays.
Here you'll see the recognizable inclination window where you can set your goal and revive rate.

 

[allan.nyholm]

you're using hi-dpi already - the screenshots you uploaded look crisp

 

[joevt]

Hold the Option key down and click "Scaled". All the modes (except maybe 3840x2160) are HiDPI. Click "Show all resolutions". This will add modes that are not HiDPI (low resolution).
Your screenshot is HiDPI so you must be using HiDPI already.
You can take a screenshot of the entire screen by pressing Command-Shift-3. Then examine the dimensions using Get Info... in the Finder.app or use Preview.app. If the dimensions are twice as wide and twice as tall as expected, then you know it's HiDPI.

 

[shamole]

Thank you all for your answers. I'm using HiDPI indeed, now I just need to figure out if I prefer 1080 or 2560...
Thanks!