The app can simulate several types of approaches.
Standard ILS approaches have a glideslope angle of 3 degrees with a full scale sensitivity of 0.7 degrees from the correct glideslope and a localiser that has a full scale deflection of 2.5 degrees each side of the centerline.
The ILS App has these values as standard, but they can be modified in the settings page to simulate:-
Also, for safety, the touchdown point can be moved into less congested airspace and additional height can be added to the touchdown point for greater terrain clearance and to avoid transgressing low-fly rules. If you add 1000ft to the approach elevation then the approach indications will be exactly the same as approaching an airport that is 1000ft higher than it actually is.