Not necessarily, depends what’s an “upgrade”. You’d have to go for more GHz, not more cores. I dont think MSFS spreads RdrThread over multiple cores, so you’d really need faster core rather than more of them. Also even with faster cores, nothing guarantees that you will no longer be CPU-limited, especially if you have an awesome GPU.
Also, I’m confused, your screenshots in the top post show Limited by GPU, not RdrThread.