A lot depends on whether the Hezzies launch a major attack and whether they will do so knowing some of those US bases in Syria, Iraq, and that little corner of Jordan, are positioned to go after their logistics from Iran. Assuming of course that Biden would give the word instead of trying more of his ineffective risk management.
If Hezbollah goes all out (launching missiles as fast as they can) and the US sits back, I can see Bibi dusting off a handful of nukes.
When Israel does that, Iran will respond with everything, including chemical and biological. Why wouldn’t they? The Samson Option will kill more Jews than Hitler did.