How do I get a channel ID?

API
4

user asked for the ID of the channel

Once you have the userID then you can get the follow count from the appropriate API which is also on the same page that I linked to.

And directly beneath the Get Users docs

You want to_id for people following a channel

https://api.twitch.tv/helix/users/follows?to_id=26610234

For example, then read the total from the response

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