To gain territory you need to attrite and degrade the enemy response. This does not require massive number nor a "x5". A basic example: you blow up the Kerch bridge, all supplies to Crimea have to make a dangerous route of hundreds of kilometres more. You have killed 0 people, but the frontline is not getting ammo and they are forced to retreat.
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I don't want to piss in your Cheerios, but when the 'Ukrainians' went full al-Qaeda and did the suicide truck bombing back in 2022 it stopped rail traffic for a whole two days or something IIRC. Vehicle traffic was inconvenienced by having to share a span while the collapsed one was re-built.
Supposedly there was a later British attack with Storm Shadow missiles, but info on that is sparse at best. May even be just another 'Institute for the Study War'
(familiar neo-con Jewish clans working their American gimps) fantasy.
In any event if/when necessary there are ferry boats that can work the straights as they have for about 100 years. But even then, why bother? The alternate route through now-Russian Federation properties adjacent to Crimea and all the way over and up into the Motherland are not much more dangerous than any highway in the West.
This is me questioning why people do not seem to understand the concept of "example" within a theoretical discussion and if BA's latest answer is an very effective attempt to win the "poorest math award" on this thread