How we can have different validation on same input field with regex or any other solution?

I am trying to apply some validation checks on my input field . Here is query i am trying to solve
We have input field which can have number of 3 different lengths.
If user start from number A (will be start with +92) its length will be 13 if from number B (will be start with 92) then 12 and same A (will be start with 0) with 11.

On all the number formats length and format should be checked and if user wants to apply without these format we will show error message.

How length of same input field will be changing with number formats and validation checks will be performed?