Can you try pressing ctrl+shift+f2 from within Kitty and then adding font_size 20.0? That will make sure you are editing the same config file Kitty is using.

If that doesn’t work, I’d try deleting the config and then try again. Kitty should automatically create a new config.

https://sw.kovidgoyal.net/kitty/conf/

Ctrl + Shift + - should decrease the font size of the current terminal, which isn’t what you are looking for, but could be useful while you sort it out. Is it possible that the font in the config doesn’t exist, causing this issue?

I used kitty-cat to edit fonts

https://github.com/adi1090x/kitty-cat