FWIW I recently installed a GRX 46/30 11 spd crank on a road bike with 68mm BB. I had a Di2 FD and the FD was both
too high on the 'braze-on' mount and would not extend out far enough to reach the 46t ring. Solution was to use an FD dropper which lowers the
FD about 6mm or so on the built in FD mount ( available from either FSA or Amazon) and machine a solid $12 5/8"
diameter 6061 aluminum bar (Home Depot) into 8 2.5mm thick washers to put between the chainrings and the DS spider. This moved
the chainrings inboard enough for the FD to reach the 46t ring. Mods worked perfectly.