Is it okay to keep my margs as 0.9 inch instead of 1 inch for my SOP
It may or may not be noticed. It may or may not be important. No one but the recipient can say for sure. You don't want a reader to be irritated with you.
So, I have a suggestion for you. First reformat it to the required standard. Then rewrite it to fit the two page limit if that is required. You will probably gain from being just a bit more concise in your wording. Don't just make it awkward. Rethink your phrasing and be more precise.
Less is More.