Yes, but it will be smaller than the 6/7/8 line. The overall dimensions haven’t been leaked, but a 5.4” screen is 93% the size of the 5.8” on the 11 Pro. If we scale the outer dimensions by the same amount, the 12 Pro should be 133.8x66.4 mm, which is in between the original SE and the 6/7/8 lineup.
Edit: after re-reading the leaks, it seems like the vanilla 12 is getting the smaller screen and not the Pro. So maybe we won’t have a smaller phone with square sides.