I am not sure that there is any continuity, per se, in the size of the adjusting screws between brands ...
If there is, then it is about 1.5mm ...
Some the adjustng screws thread into a 'nylon' block on some derailleurs ... in those cases, you can possibly substitute a small "wood" screw [e.g., the type that hold plastic VCR/(VHS) tape cases together].
YOUR best option is to go to a bike shop with EITHER your derailleur and/or bike OR more specific information.