Sometimes, older / archival Great Performances and other PBS programming are available though the PBS Passport service, a monthly streaming service. As answered above, going to PBS.org and connecting to your local channel will allow you to see what is and is not available. In my area, Intimate Apparel is currently available for streaming for free.
FYI--Live from Lincoln Center broadcasts are the only ones that consistently are only broadcast one time, so set one's DVR accordingly. They are rarely available for streaming later, although there are some exceptions, especially during the height of the pandemic.