You probably can roughly estimate your expenses in retirement by considering what you would like to be able to do. Here is a large item, health insurance, depending on your age. Medicare isn't too bad, they take it out of my SS "check". But before I qialified for SS, I paid it myself, and before that I paid for retiree health insurance, which was heavily discounted from market.
Try and get your domicile paid off, if possible, then you have maintenance and property taxes. Figure your CORE expenses, things you HAVE to have and pay, food, etc. Then see how much room there is for travel, golf, wine tastings, car replacement/maintenance, etc. I think when I was near retirement, I was pretty close with my estimates. When I was 40, I was not.
Now figure inflation, somehow. You can't earn 2% on your savings if inflation is 4% and figure you're breaking even. Then you'd have income taxes on any income, investment or otherwise.
I read all kinds of "guidelines" about how much one can withdraw from "savings" safely, and they are mostly bunk IMHO. The old rule is 8%.
Here is another tidbit I learned from my "financial managers", invest SOME of your nest egg in aggressive stocks, Nvidia, Apple, XLK, whatever. SOME. Don't adhere to that 60-40 rule, it's too restrictive. Keep around 5 years of income needed very liquid. Invest the rest, I do like a blend of ETFs, but if you have money you don't expect to need for say 15 years, you can invest that aggressively, and forget it. Then rebalance your portfolio fairly often to make sure the aggressive part didn't grow faster and become a major part.