I would like to change the font ligature only on VS Code, instead of changing the main one (font family), is it possible and how to do? I have Cascadia Code and I would like Fira Code font ligatures.
I tried to change the font family in the settings but the attribute editor.fontLigatures is a boolean and change the ligature with the attribute editor.fontFamily. So I don't know how to make the ligature different than the font family.
Can I have the font ligatures of another font other than the currently selected font family? For example, can I have Cascadia Code as the font family, but use the ligatures of Fira Code?
Ligatures are baked into the font. There's no magic way that you get the "ligatures of one font" and apply them to a different font. What you're asking for might technically be possible, but I'm not aware of it being implemented in VS Code, and the idea of mixing fonts in the same monospace character grid sounds messy.
You may be interested in a tool like https://github.com/ToxicFrog/Ligaturizer, which you can use to build a new font where the ligatures from Fira Code are copied into the new font along with the contents of some other TrueType or OpenType font.