it is true that gears 5 has excellent optimization, so it's not surprising that all systems run it fine, same for forza horizon 4
xbox studios might fine tune their own games to hit 1080p 60/4k 60 for both s and x consoles respectively, but multiplatform games clearly target 1300/1440p 60 fps for ps5/xbox. in this scenario, series s never gets away with 1080p 60 fps
at some point, i'm fairly certain xbox studios will also target 1440p 60 fps for the big ones. otherwise, we will be having games that look like gears 5 (let's be honest, its not that impressive graphically) for the entirety of generation (even the last of us 1 remaster looks leaps and bounds better than gears 5 and that's telling a lot, since that game was practically designed to run on a ps3). i will give forza horion 4 props though