Thank you for the question.
The simple answer is yes, breast implants can be overfilled quite a bit. However, this may not be in your best interests given that the breast implants may be quite firm and may result in an aesthetic appearance that you are not pleased with.
I would suggest that you communicate your goals clearly with your plastic surgeon; use his/her years of experience to guide you in regards to the best breast implant size/profile that will likely meet your goals. In my practice, I prefer the use of goal pictures to help with this communication process.