Paint the inside of the arch Snowbound; meeting the baseboard and hall paneling it will present as trim. Use the same finish.

An idea, which I prefer, it to install flexible trim, and then paint it as woodwork color. Comments say it an easy install. Here is a photo of how it looks:

And this post:

https://curatedinterior.com/arched-doorway-ideas/

Thank you @tracefloyd, yes my question is what color to paint the inside of arches since hallway will have Contented on top half and Snowbound on bottom wainscoting and trims. Other side of each achway in next rooms will be Neutral Ground.

Is your trim in the adjoining rooms also Snowbound? Have you looked at the suggested coordinating colors on the SW website? Coordinating color for Snowbound is Colonnade Gray, LRV 53. LRV for Contented is 52.

Have you considered choosing one paint color for both upper and lower in the hall?

Some choose the dominant room for the arch transition paint if there is a color change between rooms, so it could be Neutral Ground for the two arches. The small arch showing the three room doors, the wall here could be your upper hall color. If I’m understanding your photos.

If interested, there is a review video on YouTube or just Google it, for Neutral ground by Jacob Owens Designs.

IMO use one color for all the walls and arches and the white for the trim including the wainscoting.

https://thelandofcolor.com/what-color-to-paint-the-threshold-the-transition-between-rooms-when-the-rooms-are-different-colors/

@Marylee H thank you so much, the article is so helpful! Looks like we need to wrap the chair rail into each threshold to maintain the wainscote look in the transition arches. Back to the drawing board!

Yes, I find it very practical, because it’s so reasoned. 🌈