If Iran and Israel break the ceasefire and get back into conflict, especially with the US getting more involved, how do you think that would affect Bitcoin?

It depends on the scope of effect to the global market. Bitcoin behaves almost the same to the global economy on the initial impact of the war but it easily recovers compared to the stocks that makes it more resilient on crisis.
You can use other major global crisis such as pandemic, war and other conflict that affect global economy as basis on the Bitcoin behavior during that time.
You will see a temporary dip and recovery immediately. Nothing to panic about. Just hodl.