The size of the periphery image will vary across different Intel® Quartus® Prime Pro versions. However, it will never exceed the recommended QSPI flash size for the periphery image mentioned in the Intel Agilex® 7 FPGAs and SoCs Device Data Sheet and the Intel® Stratix® 10 Device Datasheet, which is 256 Mb for Intel® Stratix® 10 and 128 Mb for Intel Agilex® 7 devices.
This information will be added to future versions of the Intel Agilex® 7 Device Configuration via Protocol (CvP) Implementation User Guide and Intel® Stratix® 10 Configuration via Protocol (CvP) Implementation User Guide, respectively.