Font size above 12px looks blurry and not sharp

[nextiadx]

I have 2 screenshots here. One with the font size set to 12px and the other with the font size set to 16px

[stgiga]

Actually your screenshot says pt, not px.

UnifontEX is 8x16+16x16. UnifontEX visually should behave identical to regular Unifont. Including its scaling behavior. Let's just say that the platform you're using and the screen type make a huge difference. Back in 2017-2018, the Windows 10 PCs I ran it on at school hated it, literally segmenting the font if scaled badly, even at 1080p. Meanwhile a 2013 MacBook Air at 1440x900 Retina handles it MUCH better. The bigger latest Intel iMacs render it beautifully. Windows 10 and especially 11 on a Hi-DPI display handle it better than old HS Windows laptops.

Even my 2002 eMac on Panther handles it fine.

iOS and Android, plus the HiDPI Macs and schnazziest Windows computers scale it beautifully. The Kindle Touch and newer Paperwhites also scale it amazingly with Amazon's own font scaler.

Linux scales it gracefully.

What I consider bad is where the font gets broken up in a slatted way, or diced up. This behavior was infamous on those school Windows tablets.

Sure, blur is bad, but remember that Android on my 1080p phone scales it beautifully with only grayscale AA.

Most importantly

It looks sharp on MY Linux install.

[diaowinner]

It's recommend to disable RGB subpixel rendering and use grayscale instead. I'm not good at Linux, but there should be some tutorials about how to config subpixel rendering.
And you misread point as pixel. Generally 16px is 12pt.