Simulate personal income tax for self-employed persons in secondary occupation

I would like to estimate how much tax I will have to pay on my income in 2024. I do have a profit calculation for my self-employed secondary occupation, but I was wondering if I could estimate/fill in/simulate my income from my main occupation as an employee somewhere, so that I can get a more accurate picture. I am considering incurring some additional costs in 2024 to do my profit, but I would like to have an idea of what to expect (first year with some profit).