Individual or team extensions are not possible for peer reviews. However, it is possible to extend the peer review period.
1. Go to the assignment that you hope to extend the peer review period for, and scroll to the bottom. You will see the link to 'Evaluations', and click on the 'Edit' button on the right.
2. This will bring you to a page that allows you to change the date and time when the evaluation period starts and ends. Modify these accordingly.