I have a chin that goes straight into my neck with no jaw definition. What procedure would help me with my turtle-neck? (Photo)

From the 1 very limited photograph, it appears that there is a recessive chin profile and fat deposits in the neck located above AND below the platysma muscle. Consider placement of a chin implant and a neck lift procedure. Liposuction can only accomplish removal of fat deposits above the muscle, while surgical extraction of the fat deposits is required below the platysma muscle which also includes a platysma -plasty. No skin removal is required. A chin implant can be inserted through the very same incision under the chin.

You have a lower jaw which is underdeveloped; so 'just' liposuction may be disappointing in its effect. You can have a more complete assessment, of course, but a chin surgery to 'extend' the distance from the neck to the chin point is needed to 'flatten' that area alongside the liposuction.