For some organizations, it makes sense to limit who can create Microsoft Teams channels. By default every team member can add as many channels to a team as they want up to the maximum of 200 channels per team. This has the possibility to lead to a lot of content duplication and confusion about where to collaborate. If a team owner chooses to prevent team members from creating channels, it is important that they have a quick way to request a channel or else user adoption will suffer.
This video and these instructions will teach you how to create a Flow that uses SharePoint for team members to request a channel, then sends an approval to the team owner, and creates the channel if it is approved.