As with all purchases that are managed by Apple when made in the app, you can request a refund here:
Request a refund for apps or content that you bought from Apple - Apple Support
In most cases all transactions in the App Store are final, but at times Apple may provide a compassionate refund. If you have trouble with the app or its services, you should contact the App Developer for a resolution to that problem. The support site for the developer is available here:
https://www.onluxy.com/luxy-dating-help-center.html?srsltid=AfmBOoo9LmwzcCyYJVjdYbJVioP2lVUxEFT-NNecrmLYGkf8kZVx1egC#/
Some apps also have a free trial to test the service out first and for those that do not offer a free trial, it is not possible to try the service and then get a refund to create your own free trial.