In the old Lightroom when I exported photos I was able to have quite a bit more control on resizing photos. Now, in Lightroom CC, I'm having troubles. When I go to File, Save To, there seems to only be Small, Full Size, and Custom. And in Custom I only have a long side pixel option. Help!!
Version 1.1! . . .
In the mean time - - - Edit in Photoshop to any exact size.
You will then have the original size + the resized images in Lr.
Unfortunately, simply not available at this time. You can still do this in Lightroom Classic! Or, as stated above... Photoshop
Incidentally, a lot of people still consider the "old Lightroom" to still be pretty much mainstream. After all, it is still being supported, updated, and added to. It certainly hasn't been done away with.