Warantly period and coverage after resignation

I am leaving my current job. I have built tooling to automate ML processes, document everything, and transfer knowledge. Nevertheless, these systems are not battle-hardened yet, and those I am transferring to are either DevOps who know little ML or DS who have poor SWE skills. I suppose they would need my help later down the road. I already offered that I would be available for quick chats if they needed me.

I was wondering what the norm is in handling these scenarios. Do people usually offer free consultation as a warranty, and for how long?