The IDF has a robust decision making process, in excess of a single “ratio” approach. Here is an article that talks about an aspect of this:
http://law-disrupted.fm/idf-lawyer-advises-war-gaza-military...
>> They also discuss the three cardinal principles of targeting: distinction (which prohibits intentionally targeting civilians or civilian objects), precautions (which requires taking all feasible measures to mitigate civilian harm), and proportionality (which for each individual attack requires balancing the anticipated military advantage against the expected civilian harm) and the rules, procedures, and policies the IDF has in place to follow these principles in every attack.
> Given that Israel also does not seem to acknowledge the 30,000+ lower bound on total deaths from IDF attacks in Gaza, it's entirely possible that Israel's ratio could be as low as 2 civilians per combatant in aggregate. But it’s worth noting that this would still be much higher than anything used by any “Western” military
The most comparable recent US engagement was destroying ISIS in Mosul. The US had a 2.5:1 civilian combatant casualty ratio. Source: https://twitter.com/SpencerGuard/status/1786612914117349769#