Start with the drains. There should be four. One at each corner. Gently blow them out with compressed air. Plugged drains are 90% of sunroof leak issues. Sometimes the hoses shrink an come undone. Try to verify the hoses are intact and open. It may take a helper to figure it out.
^^^^ what he said. My front driver side drain tube came unhooked. Me and a buddy dropped the headliner enough to get a hand in there and hooked it back up. We put a zip tie on for extra security. No leaky anymore.
Not into the car! DUH lol. They do leak into a channel which leads to the drains. Then the hoses take the water out the bottom of the car. Around here I've seen screwed up hoses rust out rockers and quarter panels! Watch This.