Let’s draft together the pattern of this shirt.
Start from a raglan block with darts.
Draw the waistband on both front and back raising and lowering 5-7cm from the waistline, then draw the bodice line a couple of cm longer then the waistband line to get that round effect on the side seam.
Get the back bodice and trace the waistband (marked with red lines) including the dart.
Trace also the back bodice making it straight from the armpit down, and not considering the dart volume.
The bodice will be slightly gathered into the waistband.
Cut through the waistband dart and close it.
Copy the new shape.
Get the front and do the same thing on bodice and waistband, but also separate a 3cm strip from center front to be cut in the contrasting fabric.
Get the sleeve, do the overlap thing for sleeve and cuff, straighten the sleeve that will be gathered and copy the cuff separately.
On the sleeve, draw two parallel lines to the center that will split the sleeve in 4 parts: from the left, the second and third will be done in contrasting fabric.
Draw a two pieces collar (minding that there is no button stand) and a rectangular piece for the waistband knotted at front and your pattern is ready!