If you are playing the game on PlayStation 4, you will be able to continue playing it on PlayStation 5 with backwards compatibility.
This also means your save files from the PlayStation 4 will be compatible and you will be able to pick up the game at the same point where you’ve left off (as long as you are using the same PlayStation account).
There are 3 different options:
1. Connect to your PlayStation Plus account and upload your saves or
2. Transfer your data via LAN cable or wireless connection (WiFi) or
3. Use a compatible storage device to copy and transfer your saves to the same PSN account on PlayStation 5.