I have made a muslin for a jacket (Vogue8701). It has a fairly wide neckline. The collar fits close to my neck at the back but it sits out quite far from my neck at the sides. On the model, the jacket fits close to the neck at the sides. I’m not sure what alteration to make to get the collar to sit closer to my neck.
One thing to note is that I need a narrow shoulder adjustment of 3cm which I took out at the princess seams. This didn’t affect how the collar fit though.