This video was recorded using version 2021.2
To style a button up shirt with a tied hem effect, use internal lines with shrink applied to the stitching. Optionally, to enhance the look, use a separate pattern piece.
Here are some important points to note:
Lower the grid size to 0.3-0.5.
Use the Focused Effect of the 3D styling tools while adjusting the knot.
For a tighter knot look, consider reducing stitch tension.