to get in to the dev console go to settings and at the top they is a big banner that says "settings" click it 5 times and it will say "dev settings enabled" if you want to turn this off do the same thing again. there once you what to get in the dev console tap the screen with 3 fingers or on a laptop press ` which is under the esc key.

the following commands are from @Korzalerke2147483647

Display CoM in-flight

AircraftScript.set_DrawCenterOfMass true (set to false to disable)

Display other circle thing idk what it is

AircraftScript.set_DrawAerodynamicCenter true (set to false to disable)

Change fuel quantity

AircraftScript.GiveFuel 0 (in liters, negative numbers remove fuel)

Change velocity

AircraftScript.set_AirSpeed 0
(in m/s, makes the plane move at the set speed in the direction it's facing)

AircraftScript.SetVelocity 0,0,0 true

(in m/s, the numbers are x,y,z coordinates, accepts negative values, the boolean at the end is required but seems to not matter if it's true or false)

Make the game dark at daytime

Light.set_enabled false (set to true to reverse)

Raise the water level
/Water>Transform.Translate 0,10,0 World (in meters, negative numbers lower it, change the 10 to whatever you want)

Delete the sky
//SkyDome_Low(Clone).SetActive false (set to true to reverse)

Delete the water
/Water.SetActive false (set to true to reverse)

Delete the dev console
/SimplePlanesDevConsole.SetActive false (you'll have to restart the game lol)

Delete YOURSELF!
/AircraftContainer.SetActive false (set to true to reverse)

//maincamera>camera.set_depth 10 ( which gets rid of the hud helpful for taking screenshots) found by @Cannabis

hope you found this helpful.