Quite the opposite. The 90’s everything was attached to frame rate (which is why you have to have limiters on DOS Box and all that to prevent people from flying through walls with a simple tap of a button). Now everything is based on TIME.
If Client A runs the game at 120FPS and moves at a speed of 100 units per second for 0.5 seconds you get:
DeltaTime (0.00833~ - which is 120Hz) x 100 x 60 frames (120Hz * 0.5) = 49.98 units
if Client B runs the game at 30FPS and moves at a speed of 100 units per second for 0.5 seconds you get:
Delta Time (0.03 - which is 30Hz) x 100 x 15 frames (30Hz * 0.5) = 50 units
So Client A and B are pretty close, despite having wildly different performance locally. Client B is going to have slightly larger jumps in numbers because the DeltaTime is larger (and thus the updates less frequent) - but Client A will have a smoother update flow and less janky interpolation.
The server itself could be running at 120Hz (Valorant does this I believe), or as low as 15 - 20Hz (common in MMOs). As long as the server update rate is greater than the rate at which traffic comes in to the server from a specific client, thus ensuring a timely response to the client - you’re golden on your end. Internet Round Trip Time (RTT) will always be greater than your client + server refresh rate anyway (20ms is FOREVER to a local machine, but insanely fast for a net connection).
I think it’s your concept of “Game State” that is confusing you. Actors don’t continually tell the server “Hey, I’m here at XYZ”. Rather they send input or small updates to the server when the user does something they are interested in, the server then validates/moves the character and reports that delta to other clients. It can also batch those updates up so they are independent of the local framerate (if you only need 10Hz for movement updates - then that’s fine, clients can interpolate the rest).
In the end, Client A, and B will have similar experiences - Client A may be a bit smoother and purely client actors will benefit from smaller delta times (cloth, particles, foliage, etc), but all the “core” stuff related to gameplay will be available to Client A/B at the same rate and at roughly the same experience (enemies will appear at the same location at roughly the same time, treasures will spawn at the same time in the same place, etc).
Network programming (especially in UE) is all about tricks and how much you can get away with bandwidth (network traffic is costly and takes time) / update rate (server CPU time is at a premium) without breaking the game or the user experience.
EDIT: I should point out, that in my math above, I’m assuming a constant framerate - however, that doesn’t matter. If the frame rate went higher/lower for a frame or 2 (or 20, or 200), the delta time would raise/lower with it and we’d still end up at the same point at the end - because time is our scalar/base.