At this rate, Iran's best playbook is to tank the hits, mobilize the population, and mine the Gulf.
Land-based attacks against US bases in Iraq are more likely to succeed than ballistic missile attacks against Israel.
Depending on how many airacraft US is going to dedicate, they can achieve complete air superiority over Iran and complete destruction of Iranian IADS. The only part that's going to be missing from the Gulf War is the ground element.
If they get into a ground war, Iran should use the full lessons learned from Ukraine-Russia conflict and go all out with ATGMs, FPVs, USV boats, ASMs, suicide bombers, mini-subs, etc at close range in Iraq and the Gulf, from a purely military POV.
As North Korea proved by sinking the Cheonan, an anti-sub frigate, with a sub, mini-subs are extremely difficult to detect in shallow coastal waters. Iran just has to commit. Either lose the subs pierside and the crews to airstrikes, or trade 1 for 1.
You cannot negotiate for anything that you can't earn, 90% of political negotiations are actually just formalizing gains.