How to find the file size of one airframe

I am selecting a flight controller to build a quadplane. Although the “Qgroundcontrol” contrain the airframe of quadplanes,I cannot find the size of the quadplane’s airframe. Can anyone give me a help?
Here is the instruciton of building a quadplane, which I use

This RAM of pixhawk 2.4.8 is 256 KB, but that of Pixhawk 4 is 512 KB, so is 256KB RAM big enough for running the airframe of a quadplane?

Thank you