No that is not the function of legendary resistance as implemented. We once had a subsystem in d&d that was there to eliminate "win-button" spells (and sometimes abilities), that subsystem was called Spell
Resistance & worked so well that casters tended to fork their build very early on to either specialize in other spells that were weaker or more group friendly (ie force multiplier stuff for the party & minor debuffs for monsters that fell well short of "win button") vrs being specialized for damage & the ability to be more successful in overcoming SR.
Legendary resistance impacts literally any ability with a save resulting in what often feels arbitrary & capricious or singling out a particular player who just opts out of contributing in any meaningful fashion beyond phoning it in
Having trigger conditions would accomplish that, the current implementation does nothing of the sort.
Legendary resistance does so little to accomplish that it would be a stretch to even make the claim that it does so even a smidge.