Due to Jira Cloud limitations, we are not able to provide you customization of the screens as we have on the Xray Server. For example, when you create an issue type Test, only after that you are able to see the Xray panels, like Test Details (where you can change the Test Type, add Test Steps, etc...)
You may find on our documentation all the details regarding the Custom Fields and Screen configuration on Xray Cloud,
Custom Fields and Screen Configuration