Setting up CICD for ADF is little lengthy process.
You have to link Dev ADF to GIT as you already have done. And create empty UAT & PROD ADF in Data factory mode.
Do the test changes in Dev ADF in local branch, merge the changes from local to master branch. Open pipeline, select master branch and publish the changes so that these are available in separate adf_publish branch.
Create a release pipeline and deploy changes from adf_publish branch to UAT & Prod ADF. In release pipeline, you can configure the values in such way that while deploying it will use UAT & PROD specific variables such UAT & PROD SQL server name, or key vault URLs etc.
Refer these and give it a try -
https://learn.microsoft.com/en-us/azure/data-factory/continuous-integration-deployment
https://www.youtube.com/watch?v=cLf3nAiGG3Q
----------
Please don't forget to Accept Answer and Up-vote if the response helped -- Vaibhav