In more concrete terms, it’s better to keep the state of charge between for example 60 to 30% compared to for example 80% to 15%. Big cycles like 100% to 5% are the most damaging over time.
I think that was the case for GM Bolt years ago, but batteries cost a lot of $$ and you won't see more than 5% reserved for buffer these days -- or 95% usuable capacity.
Tesla also had software lock limiting access to extra battery capacity on the Model S -- 70KWh instead of 75KW, or about (7%?). No point in carrying around extra weight that costs $3,000 to unlock, but it probably helped prolong battery life.
If you charge your phone to 100% using a ~4C 60W fast charger you're going to utterly fucking destroy your battery compared to someone who charges to 80% using a 0.5C wireless charger.
In my experience, vacuum cleaners and smartphones are designed to destroy the battery as fast as possible, while most car manufacturers will have a big buffer and lie about the true 100%. With some notable exceptions though, like Tesla that allows to charge to 100% with some scary warnings or Nissan that designed some early Leafs battery pack without longevity in mind.
I'm lamenting the fact that we have to do this even though film capacitors can be drained from 100% to 0% without damaging the capacitor or reducing its capacity. This is far closer to how you want an energy storage device to operate. Aside from the fact that film capacitors store about a thousand times less energy by every metric.