You might be interested in this book:
AbeBooks.com: 2022 National Painting Cost Estimator: Unread book in perfect condition.
www.abebooks.com
I bought it when I was just starting out. It helped me tremendously from the get go. Now, since I have been doing this for 10years, I have my costs down pat. It essentially shows you how to calculate by square foot cost, not floor but walls. Then you add items like base, trim, by linear foot. Sooner or later you will have pretty much all the costs in one easy sq/ft cost per wall sq/ft.
I believe what you might be asking for is cost per sq/ft of floor which is more of a range, since it doesn't factor how high the walls are or if doors are 8' vs 7'. Using a method like this would yield the same result for a room that is 8' ceiling or 10', 12'.
Whatever you use, you need to make sure you are factoring in overhead and profit, not just labor and materials. Those figures will be yours and yours alone, as my costs may be more or less than yours.