Yup. Lipping is perhaps 75% of brass work. Tonguing -- double or even triple tonguing -- is perhaps 15%. I could triple tongue in High School, but these days I'd settle for playing well enough to please myself.

My brother plays trombone, bass and treble clef baritone (euphonium), and can fake it on bugle and trumpet. As I said, I just play to please myself.

It's hard to describe the lip work. You "buzz" to set up the vibrations that create the note, and the amount of pressure, smallness of the lip hole, and other things create higher or lower notes.

Consider the bugle or the hunting horn or any horn without valves and with fixed tubing -- you only have your lips and tongue to create the notes, and yet you can achieve a very wide range of sound.