Hello Marvin,

Currently it's not posible to skip certain registration step on the basis of plan.

There is an alternate solution, you can create different-2 profiletype (create registration step accordingly) on the basis of plan.
Then You need to use Payplans Easysocial Profiletype, which will assign profiletype on the basis of plan selected. So when user register , profiletype will be shown on the basis of plan they selected.
Refer below mentioned document for more details.
https://stackideas.com/docs/payplans/administrators/integrations/easysocial-profiletype

Let me know if you have any query or correct me if i misunderstood.