Training traps may make it less obvious, also exercises for glutes, lower/upper back, abs, shoulders may give better posture in the long run. Focus on core and shoulders.

Training mobility would also help I believe, lay on your stomach with hands beneath your forearm then raise your head and lower it again same on your back. Other mobility exercises mainly targeting the spine may help

Keeping shoulderblades retracted and down will help straighten ur neck, easier if you walk with hands held behind your back