As you know, OCI migration (IaaS) is just migration to a different Hardware i.e. Oracle Cloud Data Center.
PaaS i.e. Oracle Cloud ERP or Oracle Cloud Applications is a close to a re-implementation of your ERP. You need to ideally choose the right partner or Oracle Consulting itself to assess your EBS first. Once done, they will suggest you the effort estimate and also the challengers you might have in migrating to Oracle Cloud.
Have a look at below article for a brief overview:
If you want to move EBS to the cloud, there is only 1 option which is to go on OCI (Oracle Cloud Infrastructure) as IaaS (Infrastructure as a Service), where you will have a database server and an application server similar to what you already have on premise but on the cloud. In this scenario, you have access to those machine exactly the same way as you do today. Oracle provides a feature called "lift-and-shift" which allows you to move the entire EBS "installation" to these new machines.
PaaS (Platform as a Service) is not an option for EBS.
Now if you were talking about going to a SaaS ERP, which I don't think you do, then a full reimplementation would be needed to go to Fusion Cloud Applications. As this model is all SaaS, there is no customization or access to the database server or application server.
Hope this helps.