Outside of premium channels like HBO, Comcast does not offer a-la-carte channel choice. I don't think even the non-cable services have anything like that either. The networks are VICIOUSLY against it.
Hi, grandprix123. Welcome and thanks for posting here for support, we appreciate it. Andyross is correct about premium channels having an a la carte option. The other type of subscription that is typically offered a la carte would be international channels. You can view a general outline of how they're grouped here: https://www.xfinity.com/learn/digital-cable-tv/add-channels. Sports subscriptions sometimes have a separate package that can be purchased as well, like NBA League Pass for example. Let us know what other questions you have.