> If you are an artist and someone commissions you to create an art piece that might be sexual, can you say "ok, but you have to ask for consent before you show it to people", and you enshrine it in the contract.

Yes. Obviously. How is that a question?

> Are you supposed to have an NSFW overlay?

Sounds like a reasonable way to comply with the condition.

> I might be hugely overthinking this.

I agree.