Matching the plate

Very new at this, been reading and I think I understand the basics but there’s a fundamental grokking that I’m missing.

Assuming we have non-ACES plates and we input them into Nuke as Utility-linear-sRGB this gives us an image which is correctly input into ACES but doesn’t match what we used to see pulling in a “linear” plate in a non-ACES Nuke session. This is noted in a few places - plates tend to be darker and more saturated. If we’re lighting a prop in 3D, and I supposed to be using this plate as is? In other words, the darker image is the correct one to match to?
In theory we have a LUT that works with this plate to give us a production recommended look to the shot, A part 2 to the question is - if production is not using an ACES pipeline and have provided, say, a cube file - is there any way to convert this to a meaningful LUT in ACES?