You can sew any desired length for the buttonhole when using 4-step buttonholes.
Four-step buttonholes are sewn as shown below.

Mark the position and length of the buttonhole on the fabric.

Attach advanced monogramming foot “N+”, and select stitch
to sew the left side of the buttonhole.
Press the “Start/Stop” button to start sewing.
Sew the desired length for the buttonhole and press the “Start/Stop” button again.

Select stitch
to sew the bar tack and press the “Start/Stop” button.
Select stitch
to sew the right side of the buttonhole, and press the “Start/Stop” button to begin sewing.

Sew the right side of the buttonhole and press the “Start/Stop” button again.
Sew the right side of the buttonhole the same length as the left.
Select stitch
to sew the bar tack and then press the “Start/Stop” button.
Raise the presser foot and remove the fabric.
Follow step 7 of One-Step Buttonholes to open the buttonhole.