The RF 70-200 f2.8 or f4 is not compatible with the 1.4 or 2.0x extenders.
Your current choices would be:
RF 100-300mm f/2.8 L IS USM - TC's can be used with full focal length 100-300
RF100-400mm F5.6-8 IS USM - TC's can be used with full focal length 100-400
RF100-500mm F4.5-7.1 L IS USM - TC's can be used 300-500mm only
RF400mm F2.8 L IS USM
RF600mm F4 L IS USM
RF600mm F11 IS STM
RF800 F5.6 L IS USM
RF800mm F11 IS STM
RF1200mm F8 L IS USM
Note, its rumored Canon is developing a new 70-200 internal focus zoom which (might) mean compatibility. It is a rumor. It has not been announced, and some have also speculated it might include a built in TC. This all speculative. This is nothing more than a rumor. I want to be sure you understand and don't delay buying a great lens based on speculation.
I shot this last month with a RF 70-200 f2.8. I was about 100ft away. Note the image is cropped.
For wildlife photography at greater distances, I would consider the RF100-400 or RF 100-500, and consider adding a TC only if one of these did not provide the reach you need. Either would be a great mate for your RP.
Bay Area - CA
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12/05/2023: New firmware updates are available.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.