The PCL Sample Round and PCL 1 (2020) questions can be found here, along with recordings of PCL 1 semis/finals. Note that neither the sample round nor PCL 1 is an accurate representation of the current difficulty and style of the tournament; PCL 2 gives a much clearer indication.
Check out the Keartamen, EEL Certamen, and recent Harvard Certamen questions for further practice.