Refreshable Clone PDBs have been available since Oracle 12.2
These are 4 blog posts I had made between Nov-21 and Jan-22 :
1. Refreshable Clone PDB -- 1 Manual Refresh (30-Nov-21)
2. Refreshable Clone PDB -- 2 Datafile Names (04-Dec-21)
3. Refreshable Clone PDB -- 3 The ArchiveLog and ArchParLog files (05-Dec-21)
4. Refreshable Clone PDB -- 4 Converting it to a Read Write PDB (23-Jan-22)
Additionally, here is a recent write-up Refreshable PDB Clones in Data Guard Environments On-premises and on Oracle Cloud by Sinan Petrus Toma (@SinanPetrus)