no Gears 5 has no performance options. it is simply dynamic 4K 60 fps, but the resolution is usually hanging around 1440p or slightly above. it only reaches 4K in scenes that are not at all demanding. but it holds 60fps very well, which was clearly the focus of the One X version since Microsoft is extremely focused on delivering at least 60fps from now on.
on Base console/One S it is dynamic 1080p30 in campaign and dynamic 1080p60 in multiplayer
nah that's just what what it is. is a simple form of ray traced AO and GI that doesn't strain hardware too much due to it only taking into account what's on screen.
that's why it is indeed Screen Space Raytraced Ambient Occlusion/Global Illumination...
usually developers give their solution cute little names like UE5's Lumen... but I don't think they have a fancy name for it here lol