I agree that you should see what he wants to do. If possible (depending on, say, insurance needs and availability in your area), give him a few therapists to choose from. If any allow a free consultation (I've had a free 15-minute call or Zoom meeting with a few in the past), take advantage of that to get a sense of fit. Let him know that it's fine to change therapists if he doesn't like the first one, and if he doesn't feel therapy is right for him right now, that's fine, too. Also, I'd let him know, assuming you and the other parent feel OK with this, that what he shares with the therapist will be confidential, unless it's a case where the therapist thinks your son (or someone else) is in danger. So that he'll feel it's a safe space to share and the therapist won't go running back and telling you everything he said.

I'm glad you're pursuing this--I asked my mom to see a therapist for depression when I was 17, and my mom said I didn't have anything to be depressed about, so she didn't agree to it. I really wish I'd seen someone then. (They did briefly have me see a psychiatrist when I was 13 for a different issue, but I didn't find her all that helpful. And it felt like they were having me see her because they didn't want to deal with my anxiety, not because they wanted to help me.)