Depression in a preteen

The past week my preteen has been quiet, very emotional and kind of depressed. I’m starting to worry bc he’s so young to be unhappy. I think it has something to do with his relationship to his father. He dad is strict but he says he’s strictness will save his life (I lost a sibling so our biggest fear is losing a child). He is also getting depressed due to covid not going to school, seeing his friends or going on vac and trips. Please help me, I’m at a loss right now and it’s making me emotional.