Face ID does not work after changing front glass only

It depends on exactly what you mean by "front glass" If you literally mean just the glass, no digitizer and no LCD, then I would expect Face ID to work as it always has. Even replacing the digitizer, I believe should leave Face ID intact. Changing the LCD, will require removing the sensor array from the old panel and transferring it to the new one to retain Face ID functions.

All of these do run the risk of the sensor assembly being damaged since some of the cables are quite delicate, but it should not disable it if the repair goes properly.