Can I check AI replies before they go out?

Yes, for email. In Settings, under Email, choose "writes a draft, and a person sends it".

When an email arrives, the AI writes its answer from your help articles and keeps it on the conversation as a draft. Your team is emailed that someone is waiting, and the customer gets a short note saying a person will read their message and reply. Press "Use this draft" to put the answer in the reply box, change anything you like, and send it. Nothing reaches the customer until you do, and a draft uses no AI credit.

Website chat is different: it always answers straight away, because a visitor waiting on your site cannot wait for someone to approve a reply. If the AI cannot answer from your articles, it says so and hands the chat to your team.