Beware anyone who tries to give you a definitely answer... it depends.. and there isn't a single answer as different games will have different hardware resource impacts. And AMD software is NOT known for stability.. unfortunately (said from an enterprise IT person's perspective, not a gamer)
As for 'best settings' that is like asking what is 'best' car. There is no answer, as it depends on requirements/expectations/desires. What is great for 1 person is not for another. Same goes for real-time video compositing.
Realistically
- Yes, you should be able to Record at 4K. Start with OBS Studio auto-config and adjust from there
- beware poor performance plugins (like some of the VERY well-known very popular gaming plugins)
- beware YouTube and similar videos that suggest settings, but don't tell you the caveats, etc. There is a LOT of bad info (as well as good.. sometimes hard to tell the difference)
Are there games out there that may be too much to also do 4K Recording on your rig? sure. Lots of variable like frame rates, color depth, etc that impact CPU and GPU utilization, etc. You also have to figure out/decide which video format to record in. AMD has been known to be really bad with H.264, supposedly gotten a little better recently?? but that may not matter depending on your workflow. Do you plan to locally edit videos before uploading? Do you Record in H.265 (as better quality encoding offload by AMD {a guess, I don't know for sure.. EposVox has some excellent videos on video encoding, and OBS Studio, that you should probably check out... though again, be aware of a recent AMD update to H.264 encoding (SDK? something.. might change recommendations of older videos.. your task is to discern the current truth)}... then export to a different format for uploading? Or will your stream provider accept H.265, or AV1 video upload?
does this sound complicated? ... it is. think multi-variant calculus. there are MANY variables all at play, impacting each other, etc. doable, you can figure it out, but no 'easy button' answers
