My guess is you are talking about having both scenarios in one map.
So the “dark cave” and an outdoor scenario.
The easiest ways is to use the built in Time of Day manager. Another simpler solution is to use the built in day sequencer with a day sequence device volume around the cave and lower the sky light intensity.
Obviously what you are asking for is a pretty hard task for a lighting artist so you want a lot of control.
Personally I like to use the “Environment Light Rig” because it allows me to control many more settings and change them to my linking.
The built in “Lumen Exposure” and “NonLumen Exposure” help you with the different platforms.
Additionally you can please additional Post Process Volumes on top of that, for example locally restricted in the cave, to boost your Exposure for this occasion.
This will also allow you to do localized colour corrections or even post process materials etc.
A personal tip from my side is to work from the start, even in Lumen scenarios, with an HDRI in the Skylight.
Depending on your skylight leaking settings, the HDRI will not interfere too much with you Lumen lighting.
But if you accomplish to choose an HDRI that has the same lighting colours as the colours you intend for your scene, you can achieve a strikingly close result with non Lumen platforms.