If it is a leasing company you can supply the following items.
IB declaration for the past 2 years
A prognosis of what you think you will convert.
In addition, they can also ask you for a down payment, and don't forget that you have to advance the VAT on an FL. All in all, it can therefore quickly increase in euros. Depending on the car you want, it might be wiser to buy a young used one for the time being.
If you still want to lease, keep in mind that you often have a contract with a decent car from 30K for 5 years. Then don't forget, because you also want to lease as a legal person, this will continue to haunt you during the term, for example when buying a home or other financial matters.
Still request without a headache about annual figures etc. I would try a car of about 15K max.