Welcome @OldGator !
I know they make them a bit smaller than actual 3’, so it would fit.
My experience and the way I like to grow makes it difficult to get around it inside the 4x4 so I’d think near impossible in a 3x3.
If you have enough space around the tent to unzip the sides, cool but I’d worry about air flow maybe as well.
Would also be tighter and easier to scrog.
I guess like anything in life there are pros and cons, you just have to weigh those out to your particular set of circumstances.
Edit: not sure the diameter of a round 100 gallon off the top of my head, but that might be a better option for 3x3. Would leave the corners open to duct in some fresh air and allow for some vortex action upward.
Edit edit: if it doesn’t fit we’ll have grassroots make a OG 90 gallon version