Calculate your new extrusion multiplier using the formula on the 1st image. Here is an example:

Your original extrusion multiplier = 1.00 and your average perimeter thickness = 0.47mm.

Your are using a 0.4mm nozzle, so your target/expected extrusion width is 0.45mm.

Your new extrusion multiplier = (1.00 · 0.45)/0.47 = 0.957

Enter the new extrusion multiplier value in the filament settings page of PrusaSlicer.