Is it possible to map pre defined data sets in PDO Mapping of CANOpen protocol
What you describe is static PDO mapping, which is also in my experience the most common. Every PDO is mapped to a data entry in the object dictionary, no matter if it is static or not. You always have PDO mapping settings and those settings point out where in the OD the PDO should read/store data at.
In case you are following one of the standardized Device Profiles, such as for example DS401 for GPIO devices, then the standard for that Device Profile specifies where your data should be stored in the OD. It will be in the Device Profile area from 0x6000 to 0x9FFF.
If you don't follow any particular Device Profile, then you can place the objects in the manufacturer-specific area from 0x2000 to 0x5FFF.
So it is actually possible to read/write data without PDOs, by doing a SDO access to the above mentioned addresses. But that's less efficient and not how you should do it.