This is actually debatable... airing more towards opinion rather than actual fact.
Yes, Gears 5 looks like a technological masterpiece across any platform... and The Coalition deserves lots of credit on making one of the best Unreal Engine 4 based games around. However, many would argue that God of War, RDR2, Forza Horizon 4, GTA V, FarCry 5, Minecraft, and the thousands of other game choices are more technology advanced than Gears 5 Unreal Engine tech. It doesn't mean they're right, or that they're necessarily wrong. Without knowing every aspect of a particular game's graphic pipeline, we can't honestly say one is more advanced than the other. Their maybe one or two aspects of one engine that outweighs all other features compared to another, the latter being considered to have the most advanced features.
Example: In my opinion, Remedy's Northlight Engine behind Control (multiplatform title), seems lightyears ahead of any other engine including the Unreal Engine, when dealing with physics and environmental destruction. Including aspects dealing with real-time scene deformation, transformation, and warping (such as the maze run) that are ungodly levels of complexity (completely unbelievable).
Point being, all engines have their strongpoints and weaknesses. So, there are points for debate on what constitutes a more advanced engine (or game) over another.