Absolute Black makes 48/32 and 46/30 oval chainrings that fit standard shimano road cranks like yours and you don't need a GRX FD. They aren't cheap though. I'm running the 46/30 on my 5800 cranks on my road/gravel bike because I wanted to keep the tighter 11-32 cassette for road but needed the 30 up front for the super steep gravel/mtn bike climbs around here. The GRX setup wasn't around when I did it, today I'd go 48/31 GRX crank for a better mix of both high and low gearing.