do you have in your level a post processs volume?
From it you can define a space where the camera have a certain Exposure .
The exposure is normally set as automatic and will change based on the environment and the amount of light detected…
I usually start adding a postproces volume from the Actor-placer
and set the exposure to manual, and set the exact amount of light i want.
Pay attention that if the camera leave the volume will go back to default.
you can have m ultiple postprocesssvolumes, or just set this one to be unbound so to work everywhere