Apparently, the answer was yes. Note that I specified full-time leads, though - seeing a lot of “such and such handles lead vocals on X”.
I once saw a 5-piece band at a dive bar in Indonesia where only 1 guy really knew how to play, so he sang lead, but also played whichever instrument he deemed most important to whatever song they happened to be playing at the time. Pretty much the worst band I’ve ever seen in my life; but since I was drinking 25 cent beers all night with 4 college girls, and he provided hours of hysterically inept entertainment, I’ve thought of him ever since then as my favorite lead singer/guitarist/drum/bass/keyboardist of all time.
I don’t think he really fits the thread though.
Kurt Cobain brought in Pat Smear as a rhythm guitarist for Nirvana later on.
There are some singers with longer careers who did lead for a while even if it’s not what they were known for. On The Blue Mask Lou Reed played lead while Robert Quine did rhythm guitar. I think David Bowie did lead guitar in at least one of his incarnations as well. I don’t know if either toured like that or if it was just in the studio.