A .338 Win Mag has approximately the trajectory of a .30-06.
It does not confer much advantage to the target shooter. Less windage with the best high BC bullets, but that is about it. I don't think I have ever seen one at a Long Range match. (NRA definition of Long Range is 800+ yards, with very little beyond 1000.)
The .338 Lapua is big and fast, originally meant for looong range sniping.
I haven't seen one of those at a Long Range match, either. It is popular for the extremely long range specialty shoots, though.
If you are only shooting to 1000 yards, you can get adequate ballistics with less recoil from a heavy .300 or a big 7mm.