how to increase QT UI fonts, all like ants?
set QT_FONT_DPI=150 xxx, not work.
You can use QT_SCALE_FACTOR or QT_FONT_DPI variables, both works and have same effect (tested on hyprland):
QT_SCALE_FACTOR=2 kate
QT_FONT_DPI=200 kate
You can also set other variables for scaling things → High DPI | Qt 6.8
And of course make sure that xxx app is really QT app 
You can also configure sway to use proper scaling factor → Sway - ArchWiki
ok. from cli work but how to from fuzzel?
You simply need to define environment variable. How and wehere – totally depends on you and how sway read variables
https://wiki.archlinux.org/title/Environment_variables#Defining_variables
in post above, set /etc/environment not work, so ask.