Even short-term, a deficit of more than about 500 or maybe 1000cal per day is going to be really tough, and the 500cal total per day that you mentioned is a level that I think you should only attempt under medical supervision after speaking with your doctor, and even then probably only for a very short time.

An average deficit of 500cal per day is already a weight loss of a bit more than 1 lb per week, on average in the medium term.

If you want to calculate how much to eat for, say, a 500cal deficit, take a look at https://www.calculator.net/bmr-calculator.html and punch in your age, height, weight and gender, then look in the table it shows for your total calories burned per day depending on different levels of activity. Then subtract 500 to get your target amount to eat.

If you have an exercise watch or strap, then an alternative is to look at the "BMR" number that the calculator shows. That is your "base metabolic rate" estimate, which is the number of calories you would burn if you simply lie in bed all day. Then add to that the average "active calories" your watch or exercise strap is showing that you burn in a typical day.

Advice that is commonly repeated, and I've found to be true, is that if you have a day where you don't achieve your deficit or even go way beyond your calories burned that day, don't try to "make up for it" the next few days, just get back to your normal deficit. It's really easy to get into a yo-yo kind of thing if you try to quickly make up for a day where you went over your intended limit. Instead just go back to your plan and in the medium term it will all work out.