There are many ways you can utilize tags but one of our favourite example is:
Multi-staged E2E testing
How to do this?
Name your QA checks in CI/CD pipeline (for example: staging tests, production tests, production monitoring test)
Create tags for each of this QA Stage (tags can be named like: staging, production, production-monitoring etc.)
Now tag various test cases with these stages so that you can easily assign QA tasks later during release cycle.