What next?

Question

Hi, i completed Sololearn's course for C++, did almost all code coaches, and i'm wondering what to do next (e.g. Where to practice writing the code). I'd like to learn C#, C, Python and Assembly (probably the hardest languages to learn, but i have the basic knowledge and want to expand it), i'm interested in game dev, cybersecurity, AI and OS.
Btw i am studying at a technical school so i know a lot about: -Databases-Networks-Embedded systems-OS(Linux,Unix,Windows)-Cryptography-Web dev-Computer arithemtic and so on