My sister just had her third who was.big and she did go into labor weeks early.
He might just be growing fast at the moment or their measurements arent perfectly precise and that could be why they left your due date the same. You could go into labor a week earlier tho, but unless they have serious issues that are life threatening to you or the baby they might just wait and see if your body can handle it since your last one was big as well, towards the end of your pregnancy your dr will ask you about your birthing plan to wich you can ask all the questions you need to. The let me go past my due date by 3 weeks before inducing me and My son measured to be 7.5-8lbs in the final ultrasound but because his heartrate was dropping and I wasnt progressing past 8cm they took him via csection and he weighted 9lb.4oz