By itself, the deployment pipeline already provides several reassurances for every change: the code still builds, the tests still succeed, etc. It also makes code coverage reports available for those specific changes.

The cool thing is: new production-like environments are deployed for every Git branch I create. When I'm working on an issue, I create a new branch associated with that issue, which will set up a new environment in which that issue's fix can be tested in isolation.

This "Review App" has its own URL, its own environment-specific build artefacts and reports, and a separate database. I can thus play around freely without interfering with production. It also allows me to verify reproducibly whether database migrations work.