Jenkins can help you with the pipeline cicd, and selenium can automate the task.
or you can try with Katalon studio.
Have you looked at the Unit Testing module on the Marketplace? This can be good for testing well defined sub microflows to ensure the logic there is correct. You can expose this to Jenkins if you are using that, or just run from the Mendix app itself.
As Quang suggests, Katalon Studio is good if you have a web based frontend to test against. There is also ATS, and that offers better Mendix support, but at a greater cost.