My understanding is that the best a VCR can do is S-Video. VHS tapes contain composite video streams, so there’s no point in a VCR coming with RGB output. You might be able to find a combo VCR/DVD player with YPbPr output, or maybe RGB output if you’re in Europe; but I’m going to go out on a limb and say you won’t be able to use it properly with the OSSC.
If you absolutely need to use this particular VCR, I recommend picking up a RetroTINK 2X and connecting the VCR with S-Video. If you absolutely need to use this VCR with the OSSC, additionally get a Portta or Tendak active HDMI to VGA adapter and use it to connect the RT2X to AV3 on the OSSC.