https://www.haaretz.com/israel-news/israel-syrian-missile-wa...
The Arrow system has sufficient range to provide coverage over Syria it’s an expensive way to deal with the S400 threat but it can be used to provide additional protection.
Israel seems to be quite adept at beating Russian SAMs Russia doesn’t have enough assets in the region to risk engaging with the S400 because Israel would definitely target them if they are used as anything more than a scarecrow.
And last time Israel went on a mission to clear Russian SAM sites in Syria it didn’t end up well for the SAM site operators.
https://en.m.wikipedia.org/wiki/Operation_Mole_Cricket_19
For the most part what Israel has been doing in Syria so far is a very limited engagement often not even from within Syrian airspace but rather using stand off munitions from Israeli or Lebanese airspace.
I’m pretty sure that Russia understands very well that other than a nuke on Tel Aviv they don’t have the logistics to have an engagement with Israel that does not end in total humiliation and the destruction of all Russian assets in the region.
At the end of the day if push comes to shove Israel can push 400 aircraft into Syria’s airspace and countless ground assets the numbers simply don’t favor Russia.
The Russian navy is also not in a shape to engage, other than their submarine fleet any naval assets they put in theater would be likely targeted and crippled if not destroyed this also includes their aircraft carrier.