A lot of it is technique. There are a lot of subtle ways to minimize or smooth out the stress on the hands, that you mostly learn by putting in a lot of reps.
Then there's just having a reserve of grip strength relative to the bell you're using so you don't have to overgrip the bell.
And finally, there's being willing to listen to your hands, realize when they're starting to get a little too hot, and having the discretion to stop before you develop a problem.
When I was fist learning (which covers quite a few years), I got thick calluses and occasional tears, and experimented with all kinds of hand protection and hand care routines.
Now, I haven't had a tear in literally years (I can't specifically recall the last time it happened), I don't get very thick calluses and rarely have to attend to them (mostly just a little filing mainly on the middle two fingers of my non-dominant hand, once every few weeks at the most).
BTW, for filing calluses, I highly recommend a glass "nano" foot file. There are many brands available on Amazon that all look basically identical. Make sure you get one that has "nano" in the description. There are also glass files that have a regular emery board texture, but the "nano" files have an etched surface that takes calluses down really easily without being too rough and leaves a nice smooth surface.