Super tight and swollen under chin incision for Corset Platysmaplasty. Is this normal?

The feeling of firmness and tightness after your neck contouring is completely normal. Especially after seven days. This will soften but will take many weeks to months to do so.

Hard to get a good visual idea without photos.  What you are describing seems to be normal postoperative swelling.  Always good to let your surgeon know what is going on and follow his/her directions.

This is entirely within the range of normal.  The maximum tightness, firmness, and woodiness may be at 6 weeks. Later you can massage the area under the direction of your surgeon. Don't do anything without checking with your surgeon at 7 days since you can disrupt the sutures. Be patient, be calm, and enjoy the new tight neck.  It will feel as if you are wearing a tight collar. If you are a runner and gym enthusiast, you will also notice in the first few months tightness as you exercise. This is also normal since the water and hard healing tissues will evaporate over weeks to months.  I am sure your doctor made some mention of these feelings, but please discuss them directly with them.  He or she will be pleased to respond to these issues.  Ask whether the doctor prefers heat or cold to ease the tightness, whether medication for tension is worthwhile in your case, and what other measures can be done while the neck is healing.