I would also be happy about accessories recommendations.
Red Dead Redemption 2 and The Witcher 3
Well, that's more a question of your personal preferences that we don't know. Do you generally want a selection of games or are you more interested in exclusive titles?
Accessories are defacto the same. How do we know what you need? But I can give you quite a few things. However, you have to know yourself whether these things are worthwhile for you and therefore also have to decide.
First a controller. Sure you got one and experience has shown that the original controllers from Microsoft are also the best in quality. But that can be increased even further with an Elite Controller. The Series 2, i.e. The current one, has an integrated battery.
If you run out of power, I recommend the original Play and Charge Kit from Microsoft. So you have a long-lasting battery that you can charge while playing using the included cable.
Then a reasonable headset is certainly not bad. There are many of them. Whether with cable or without, stereo or surround sound and then also extreme price differences. I currently use the Steel Series Arctis 9X. Wireless and good surround sound. If you can and want to spend more then my recommendation is either the Astro A50, latest version or the Beyerdynamic MMX 300 which probably has the best sound, if only stereo and wired.