I've already filed my taxes but just received 2 T3's in the mail. I'm not sure if the CRA automatically transferred these over or if I need to redo my taxes?

You can add the slips to your existing return.

 

This TurboTax FAQ tells you how to do this using ReFile: https://turbotax.community.intuit.ca/turbotax-support/en-ca/help-article/accounting-bookkeeping/filed-tax-return-still-make-changes/L992Trv7f_CA_en_CA

 

This Canada Revenue Agency (CRA) web page lists other ways to can adjust your return: https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/change-your-return.html