I have carried a full size 1911 IWB was a kydex holster. I tried a G19 in a retention holster And it was too noticeable. Even my 26 was too. Unless you wear loose clothing or a jacket I don't think it's possible.
It depends on your state's idea of "concealed". Oddly enough, here in Mass, as long as no part of the firearm is showing (even if there is a huge bulge) it's considered concealed. Other states are like that, some aren't, you just need to find out what your's requires.