The only reason I can think of to upgrade is if you use some serious, fully multithreaded software, here the big Ryzen will pretty well blast your current CPU out of the water, it'll also be a big help if you stream extensively.
For gaming and general uses, the 6700K is still a fine part, and would, most likely, be a bit quicker than the Ryzen for pure gaming.
If you DO have the bug to upgrade and can't let it go:
A SSD isn't a bad idea, it won't help your frame rate but it will make the whole system more responsive, and for most mortals there's not much difference in real world performance between the superfast PCI-E NVMe drives and the far cheaper SATA ones.
After a long while at grossly inflated prices GPUs are selling at something like reasonable sums again, and the core system can easily drive a GTX1080Ti ( budget permitting
) so if the current card is struggling, looking there won't hurt.
Or what about a display upgrade? It's the part many of us neglect but fast, high quality displays are a real boon, not just for gaming either, modern displays have various tricks to help with eyestrain and colour fidelity has never been better with even TN panels regularly showing over 90% sRGB with excellent vibrancy.