I2003 A6 2.7. Great condition. It has an issue w side mirrors. I start the car, then turn the switch that unfolds the mirrors, and rather than instantly unfolding, there is about 15 -20 second delay.

Have you replaced the actual switch panel mounted in the door? If everything else works directly with their own switches it could be the switches you use whilst driving.

start by checking fuses

The gear element stripped out inside the mirror housing

check the open position stop sensor for a fault

Does the other side mirror work?

If the other side mirror adjusts with the switch, then it could be an issue with the mirror which isn't working.
Usually a mirror has two motors, one for up/down and another for left/right. If the mirror works in one direction and not in the other, yet the mirror on the other side works in all directions, then the issue is not the switch, but the mirror.

Unless none of that is relevant and you are talking about the fold function.

If neither mirror folds when you depress the fold button, then you need to check or change the switch as the most likely cause of the issue.
If you can provide me with a picture of the switch, then I can try to advise on how to remove and replace it.

the gears in the mirror are worn either replace mirror or just live with it depending on how much they are to replace

so how u fix it ?

if you wish to "set" the seat and outside mirror, then ignition key to ON, no seatbelt, transmission in "P", no breaks. press SET at the door panel, move the seat and/or mirror to your position, then press "1" or "2", according to the key color you use ( 1 with the black key, 2 with the gray key). If you wish to fold the mirror ( if equipped with), press the button in the center of the mirror mover switch to fold them, press again to unfold.

Get a hold of a schematic and a VOM and start tracing the voltages to locate and fix issue.