Usually denoising will not kick in without enough VRAM. What I have done in the past to conquer this, is to either render the background and a character or two first, then if you have additional characters, render them separately without anything else in the scene and then add them to the render later. If not that, than a simple DAZ only solution is to do a spot render for each half of the scene and then combine them later.
In this example I select the spot render tool at the top, then I set it to "New Window" in the tool settings on the left (important). Then I select half the screen (in this case, the left half) and it will only render that half...
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The result will be something like this... then just repeat the same work for the right half. I will usually also HIDE any character (like the Alien, book etc) before I render so less VRAM is needed as that half is not being rendered. Then when I render the alien half, i will hide Sophia and combine the two halves later.
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You can also save a lot of VRAM by hiding different body parts, eyes, tongue, jaw etc... of characters that are not visible in the scene as I have discussed in here before. Every little bit counts.