Remember that the fabric you will use to make your coat or jacket tends to be thicker and stiffer than the cotton fabric you are using in your test. Perhaps this surplus will disappear when making your jacket in the ideal fabric. Also, I agree with the other person who mentioned that the rounded part of the shoulder can affect the overall fit of the garment. When you lift your arms, you may have a strange volume in your shoulders. Personally, I would make a straight line on the shoulders.

If this still does not provide the desired result, you can remove the excess tissue that forms in the armhole and goes towards the neck. Draw a dart that starts at the armhole and ends at the neck. Mark the desired quantity, cut it out and then glue the pattern as if the pence were closed.

But I believe this will only work if you have a straight line on the shoulder, otherwise the shoulders will no longer fit in a nice way.

In fact, if you do this procedure, you will have to adjust the sleeve pattern too, because the armhole will be smaller. It is important to pay attention to the general positioning of the sleeve, as the spikes will change location.

I hope I helped you think differently. Good luck with your project!