IMO, Depends on the room, the lighting & the ’darkness’ of color. Looks like walls & border / soffit are a mint green now. You have options. You could paint the lowest horizontal ’ceiling’ the color & the vertical on the soffit white like ceiling or the whole piece white or repeat what you have….

Paint the soffit the same as the ceiling. Your last picture with two different greens and a band of tan between the walls and the soffit looks ill-advised, IMO.

Definitely the same color. If you go with a different one, it will look a bit busy and make the ceiling appear shorter.

I would paint the entire soffit the color of the ceiling, so it makes the room look a bit wider and also taller.

Same color bet strategy.

*best strategy. Also, flat finish so no glare.

I do agree, on the flat finish also.