I don't think so.
I5-9600k at 100% usage and 3.7GHz, that's base clocks without turbo.
RTX2080ti seeing 90% usage
1080p monitor? No, there's something else in play here because either of those is far more capable of lower usage and still going way beyond 1080p limits.
Cpu sets the fps. It pre-renders all the frames. Sends those to gpu for finish render according to resolution and details.
Usage is the amount of resources needed by the cpu to get the pre-rendered frames. You can get 100fps at 80% usage or 20% usage, depending on the game code.
The gpu has to live upto whatever it gets sent, or not. Doesn't matter how much more powerful it it is or not, if it gets sent 100 pre-rendered frames, that's all it's got to work with.
Meaning if it can put up all 100 frames at ultra settings, it'll put all 100 frames up on low, only thing that'll change is the gpu usage as it'll require more resources at ultra. Won't affect the cpu at all.
Only way I see 1080p causing 90% usage on That gpu is if op is running 4k DSR with DLSS and Ray tracing enabled, through GeForce Experience on a poorly optimized game.
For cpu, I'd be leaning towards all core locked 3.7GHz, turbo disabled, MCE enabled and other misappropriated bios settings, almost as if there was some OC included, but someone disabled it by turning off the turbo.
Op has an overpowered gpu. That won't mean that usages will be that high, without reason. Usages on that gpu at 1080p should be closer to 30-40%, especially since op said the settings are on low, not 90%, ever.