Today, I could confirm that the transfer of owner of files got to be able to be achieved with batch requests of Drive API. When I had tested this at January 31, 2020, an error of there is no function to change the owner of this item yet (currently under development) had occurred.
But today, I could confirm that this got to be able to be achieved by the batch requests. By this, the owner of a lot of files can be transferred by reducing both the process cost and the quota cost.
You can see the sample script of Google Apps Script at https://github.com/tanaikech/Batch-Requests-for-Drive-API-using-Google-Apps-Script#transferring-owner-of-files.