Can I capture different native resolutions with the same CCD-Sensor? Im working on a paper for my university and need capturings of the same scene in different native resolutions. Im currently using the Logitech BRIO camera with OBS for capturing. 

My question is: If I change the resolution of the camera in OBS, does this result in native recordings in that resolution or is the resolution only changed in software? 

I know that it could depend on the implementation from OBS but is it even possible to get different native resolution from the same CCD-Sensor in theory? I couldn't find any information about how changing the resolution is actually done.
No, there is physically only one 'native resolution' for any hardware sensor. It is the number of physically distinct light sensitive areas on the sensor chip and is set in silicone at the time of manufacture.

When OBS or any other software gives you a different sized image it is either re-sampling using the values available from the native resolution or alternatively changing the camera resolution which then puts the burden of re-sampling on the cameras internal processing chips.

(Unless you are working with RAW output then the information lost between using a native resolution and sub-sampled resolution is going to be swamped by what is thrown away by modern compression techniques such as JPEG anyway.)