head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Resident Evil Requiem demands more optimization.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.

Optimization · Practiced Mastery
Managing scarce resources and learning authored scares that converge to routed runs.
Grand Theft Auto V leans Execution (Practiced Mastery); Resident Evil Requiem leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Resident Evil Requiem
Aiming under pressure matters but stays survivable
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Resident Evil Requiem
Enemies and stalkers follow designed behaviour, not adaptive minds
Resident Evil Requiem leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Resident Evil Requiem
First-run horror trades on scripted-but-unknown encounters
Resident Evil Requiem leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Resident Evil Requiem
Resource management and routing converge on optimal runs
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.