After market 21” or 22” alloy wheels

[Madelvic]

If I were to go with after market wheels I'd stick rigidly to the same spec as Porsche wheels. Therefore no bigger than 21 inch, same offset, same width and exactly the same size N rated tyres

[TheTraveller]

If you want to have a serious choice, you may wish to have a look what is available in the States. There is a real plethora of wheels over thee, and can be built to customer wishes ( but the cost will go with it).
On my PCM, the choice of size of wheels only goes to 21". If yours is alike, then putting larger wheels on, will upset all the settings of the car, unless fitting ultra low profiles. Which may be a little rough over the bumps.