Network Templates often provide a simplified or standardized subset of options to ensure compatibility across multiple devices or configurations. TikTok might be excluded from templates due to inconsistencies in how it's detected across different environments.
You can try blocking as per this other discussion.
Solved: How to block TikTok in 2022 - The Meraki Community
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
Please, if this post was useful, leave your kudos and mark it as solved.