This video by Yassar Seirawan gives a clear and simple explanation of the Sicilian. https://www.youtube.com/watch?v=TvipCjxqGiM
2.Nf3 is considered the main line, but what if White does something different you ask? Good question, because they will do something different. At club level White usually continues 2.Bc4. Then Black should play Nc6 whereapon White should bring one of their knights out, after that one plan for Black could be Nf6, e6, and d5. Some people prefer an immediate 2...e6 also.
Everything I read/watch says this Sicilian Defence is one of the best options for black. I understand this starts when white plays e4 and black plays c5. However from here, it is my understand that white usually plays knight to f3 .... but what if white does something different?
There is where I need help, please.
Would someone please explain or offer me a link to better explain a bit more of the foundational idea behind c5 and how to best develope from this if white makes a less traditional move?
thank you in advance.