You have a few options, in Capture One. I am assuming you are running 6.4.x?
1. Under "noise reduction advanced" use the Surface slider. This will add a lot of blur quickly and should help on the Christmas tree/color aliasing you are seeing.
This is a universal setting and can't be used in a local adjustment (I wish it could be). So you may have to work up to images and layer them on PS later on.
2. You can reduce the sharpening on the entire image, I can't remember the default for the P45+, but under the main sharpening area, move the top slider back to
about 1/2 of the default and see if that helps. You can add a local adjustment and sharpen up the rest of the image. Works well depending on your image and
how much you are trying to keep from aliasing
3. You can try the moire filter, I know this not moire but color aliasing but sometimes the moire filter will work on it.
4. Under the noise reduction main selection, try working with the color slider and single pixel noise sliders. Sometimes this will work.
Try these and see if helps any. LR may also work a bit better on the color aliasing issue (4.1) you can make a local selection and reduce noise, which will help
make the color aliasing not as strong. One of the great things about the P45+ is the clear, unobstructed resolution it can capture, and color aliasing is just one
of the things that is a side effect of such great resolution.