Is this actually true? I don't know how I would find the answer to this question without paying a team of lawyers to analyze the 40,000 word Digital Markets Act. However, my guess is that it's more nuanced.
Structurally, I think the developer program will be unchanged. iOS will still require code signing using a certificate issued by Apple. It will also continue to have sandboxing and restrictions that prevent apps from using private APIs. Apple will continue to require developers to accept an agreement and reserve the right to revoke access in the event of a violation.
As dictated by the DMA, legal agreements like the App Store guidelines will become more permissive and new public APIs will be introduced to support certain use cases that were previously reserved for Apple. But this does not mean Apple can't control their platform anymore.