It's relatively easy to change the chainline on grx cranks. I found washers at McMaster-Carr, part number 98370A015. I've also modified 1/4 inch washers by enlarging the hole and grinding down the OD, but that's a lot of work and requires more tools than the average person has. Each washer should have the same thickness within 0.003 inch and often they don't since washers thickness is not usually critical. Grx chain rings mount behind the spider, so adding washers moves the rings inward.