No. An RF lens requires an R-series camera. Your camera can only work with EF and EF-S lenses. And, it's not possible for there to exist an adapter that would allow RF lenses to work with EF-mount cameras.
No RF lenses aren't compatible with any of Canon's DSLR cameras. It is also not physically possible to adapt the lens either. RF lenses have to physically sit closer to the image sensor. But in a DSLR camera the mirror is in the way so its not possible. EF lenses can be adapted to the EOS R series mirrorless cameras. This is because the adapter puts an EF lens at the correct distance from the image sensor. Since EF lenses were designed to sit further away from the image sensor due to the reflex mirror and optical viewfinder system.
As others noted, there is no way to make the lens compatible. And even if there was, a lens with a wide open aperture of f11 isn't going to be good for wildlife unless you have good lighting, a sensor that performs very well at high ISO, or a subject that is willing to pose for you. Your t6i doesn't have great noise performance at high ISO so you don't want to put it into situations requiring operation in low light with a lens that is "slow" in terms of light performance and shutter speed must be fairly high to freeze motion.
Look at one of the Tamron or Sigma 150-600mm super zooms. Another great lens for the T6i is the now discontinued but available used is the Canon ef 400mm f5.6L Another is the ef 300mm IS f4L with the 1.4x tel-con.
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.