My company wants me to model for advertising

Since modeling is not part of your job, you don't need to help your company create advertising, and it sounds like others were asked to participate so maybe you can just say no.

As the other response notes, they'll probably ask participants to sign releases, and a release is likely to give them perpetual rights of use of the released image, as well as the right to use images you don't even like or approve. And no, since the company isn't asking professional models and has couched this as "volunteer" work, it might ingratiate you with them but don't expect to ever be paid for this modeling. Maybe you can get copies of the photos or other photos from the photographer to make this worth your while.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.