Everyone's advice will differ but I'll throw in my experience. I had a 200 sq ft room in an old condo that I put the projector in. I believe it threw around an 86' image, at about 12 ft. At the time, it was okay, but I was sitting way to close. Close enough that it would torch my eyes after watching a movie. You want to sit a good 15-20' away from your screen when you start to get to images that size. Now, I have a house and throw 106' image and can sit back a ways. I believe you want to get to 90"+ to really get the experience. My advice would be to not only worry about the size of the image, but how far back you can site from the screen.
It isn't, anyway wit 1080P you shouldn't sit further away than 3 time the image height, that's assuming you have 20/20 vision, not worse. With 4K that's twice the vertical resolution, the viewing distance recommended is 1.5 times the picture height, and with 8K 0.75 times the image height. So you very well may be just fine sitting three meters from a 1.5 meter high screen, so a screen bigger than you are considering, this is quite forgiving.