Buy the best air rifle scope you can afford. The best scopes may cost more then the rifle.
If you live in the country buy a 22 rim fire instead. If you need quite use CB long cartridges out of a rifle they are as quite as a air gun.
Unfortunately, I live in a subdivision, not the country....but with a very high wooden privacy fence and the back yard (the intended “killing ground”) sits in a sort of “bowl”, if you will; VERY private....but no way to use anything beyond an air rifle or slingshot.