You will have to look at the recommended screen size and UST PJ placement... There are also calculators on some vendor and reseller web sites that can give you some Ideas about screen size and placement along with and pj placement... Like:
https://www.projectorscreen.com/projector-screen-calculators
In my instance, the top of the AV rack is 20 inches from the floor... The PJ is ~12 inches from the wall.. Fills a 103 inch screen... The PJ can go all the way up to a 120 inch screen and in my room that would be too large, covering virtually the entire wall...
I am still blown away with the image every time I turn it on...