Where to start competitive programming?

Hey Guys, I’m SyntaxSamurai. I’m 17 years old, from Germany, I really like programming and tech in general. I’m interested if anyone could give me some resources on where to start competitive programming. I’m already able to code in C, C++ and some C#, as well as some Python. I already heard of resources like LeetCode, but I didn’t finally figured it out yet, where and how to start.