I am at Sao Paulo - Congonhas (SBSP) which has a really short runway (1940 m) and I was wondering if its possible to buy bigger aircraft with longer runway requirements and lease them out to other players? Is that even profitable?
Sure it can be done, lots of players do it.
Whether it's profitable or not depends on what you're buying and whether or not you can keep it leased out most of the time.
Make sure you buy planes that are in high-demand is the main thing. Get yourself into a model that has a long queue and people will buy/lease your planes rather than waiting years and years for one to be produced for them.
Or you can avoid the possibility of maybe having a hard time keeping it leased out by buying them and selling them outright. If you can buy in large quantities you can get yourself a good discount. And people will pay a Premium for a model on the market if it's got a long wait for new ones from the manufacturer. Combine your discount up-front for buying in large quantities along with a nice premium on the market for not having to wait, and you can easily make a 30-40% margin on a plane. When planes cost $100-200M each, making a cool 30% profit can add up to a lot of money.
Or lease it out for a few years, they'll often get returned after 6-8 years when they're due for a D-Check, then do the maintenance and sell it outright on the market. That can add up to even more profit, as 6+ years of lease income will more than pay for the plane and you can sell it for what it's worth all over again; you can get what you paid into it a couple times over. Big money.