Make your own flavored cola?

Hello. In addition to Coca-Cola, Coca-Cola Zero, and Coca-Cola Light, there's also cola with lemon, cherry, or vanilla (the latter is my favorite), but it's not always available. Is there any way I can make this flavor myself, for example, vanilla or lemon, if I buy a cola from Aldi, for example? Are there flavor drops or something similar that I can mix into the cola to make it taste similar?

Thanks in advance