Could you also say "C'est tres bon?" Instead of "Il est tres bon?"

Yes, "c'est très bon" is perfectly OK but it  is a more general statement. "Il est très bon" refers to a specific subject.

Have you read this lesson yet? https://kwiziq.learnfrenchwithalexa.com/revision/grammar/when-to-use-cest-or-il-est-elle-est-to-say-it-is

-- Chris (not a native speaker).