Have there been any new ways to make the program make the font behave in a way that you type one letter and then another and it produces a single glyph? This is for a conscript of mine.
I saw this topic mentioned on this forum, but that was 7 years ago, so things might have changed.
Yes, the usual way is with a ligature substitution, e.g. to substitute f + i → fi ligature.
See the tutorial on Adding OpenType Features