PS Sizing

I would like to know how the transformers in the PS are sized.
So far, all the information that I could find is related to the voltage requirements, but I would like to address the requirements for the current, more specifically, the inrush current.
There isn't enough information on the subject. What is the largest inrush current that a transformer could handle given that the diameter of the wire in the windings is Xmm?
How is this calculated? Or the transformer is designed to handle a specific amount of current during normal operation and the inrush current isn't an issue, no matter how large the filter capacitors are?
Thanks in advance.
Best
Soundork