Creating a font with radically different widths?

Hello, I’m wondering how to set up a font that has different widths: some very wide characters and some thinner. An example would be a 5" “A” next to a very think “B”. I see that when I paste a wider character (from Illustrator) into glyphs, it simple goes outside of the bounding box…

If anyone has suggestions on how to set this up / approach this I would appreciate it! Thank you.

Then you just adjust the bounding box to fit the outlines.