Horizontal neck lines much worse 3 weeks post neck lipo. Will this improve over time? (photos)

After liposuction of any part of the body, the skin above the are treated tends to be loose and may have some wrinkles. The skin after liposuction has to "shrink" to adapt to the new body. This process takes up to  3 months. Therefore, at 2-3 weeks post surgery, there is still healing going on. 
Patients with questions and concerns about their neck lipo healing process should contact the surgeon that performed the operation. 

It's too soon to tell what your final results will be. You may still have swelling, which can last 3-6 months after your procedure. To speed up healing, you can try adding hyperbaric oxygen, lymphatic massage, venus legacy or exilis radiofrequency treatments. To improve final results, we will often do a kybella and ultherapy about 4-6 weeks after neck liposuction to get more of an outcome. See an expert. Best, Dr. Emer

None of the procedures that you describe, seem specifically designed to address horizontal neck lines, which are difficult to treat.  Laser resurfacing, needling, PRP, and small particle fillers (eg. volbella, belotero) may be able to help.  Please discuss your concerns with your surgeon.  Hope your recovery progresses well.