Create Support Case via API Call

I am rather new at Suite CRM been looking at the API documentation
I would like to be able to create a new case from an API or curl call with a 4 to 5 custom fields in the case/ticket
is this possible?

It’s possibly without problems. You can use API 4.1 or 8. They will work with custom fields too.

I am able to do an auth with Curl

curl --request POST
–header ‘accept: application/json’
–header ‘content-type: application/x-www-form-urlencoded’
–data scope=
–data grant_type=password
–data client_id=2a30b79a-2106-70ee-9ba1-60941bd045678
–data client_secret=password
–data username=admin
–data password=password123

how do I create a new case via API /Curl?

Yes. Look at the documentation.