Should we mock in cucumber testing while testing java code. Till what extent we should use cucumber?

I am a Java developer. We want to use cucumber testing in our project. We are working mainly on creating APIs. I am good with unit testing and researching about cucumber. I am thinking about testing persistence methods - CRUD operations as an starter. My questions is that what could be the scenerios in this testing. Also should I mock the database by creating tables in the feature file. Should I use mockito with Cucumber to mock call to some other services which connects to database and server. What should be the cucumber testing in these scenerios and whats the best way to create framework to use cucumber in our Java API's project.

Also, how to populate models if not using database