RCP 8.5 was never expected to happen. It was a prediction based the entire world doing nothing at all, banning things like green tech, and increasing fossil fuel use AND even the introduction of new techs to increase the amount of available fossil fuel reserves. Afterall we only have ~50 years left anyway. To get to 8.5 we would need to expand upon this significantly.
RCP 7 was kind of status quo, which isn't even possible because Tesla is worth a trillion $.
RCP 6 is we kind of half-assed it and we never properly reduce anything, no new techs etc. This one is possible but given political climate I see this as practically impossible.
RCP 4.5 is highly likely. We have until 2045 or so until we peak. I see this happening, China has many coal power plants in construction right now. They wont be reducing. Much of the world wont be. Though around this 2045 date is when fossil fuels start increasing in price quite significantly just because of supply/demand. The cost to go non-fossil fuel will simply make more sense before this. So those coal plants in construction now, mainly by china, will be getting shut off then. The rise in temps will be roughly 2 celcius and that's completely manageable by our society. Especially given decades to respond. There are arguments that features like greenification is actually a good thing and not a bad thing. Therefore 4.5 is actually unlikely.
RCP 3.4 is where it's all at. It's literally the line we are tracking already with everything we have done. It's slightly less than 2 celcius in increase. There's no major need to declare war on china and blow up their fossil fuel operations.