While there is a global flow rate (extrusion multiplier) I think it would be useful to have a percentage box for the first layer and also infill.
While there are settings the first layer to set width and height, or better bed adhesion, it would be useful to have a flowrate override box there to increase the flowrate on the first layer.
Similar with infill, while there are various percentages, it would be useful to be able to set like 90% flow rate, or even 110% flowrate for infill only.