With the right gear you wont get oneshot. You will sacrifice alot damage for 95 maxres, a ton of stacked res and absorbbut once you wear all the right gear its pretty easy to survive.
The guys on softcore tend to go for more risk (90 res, not enough stacked or smth) but do enough damage to out-dps most of the content. And once in a while they get oneshotted ofcourse :P

When lichking was a thing back a year or smth we were doing him on hardcore just well.
Even soloed him with psnmancer after i got the dagger.

You will likely need a softcore character first to test things out... i couldbt imagine to learn everything needed from vids and guides around here and youtube.

At least 5.1 or 6.0 whatever it will be called then makes normal way harder. That will make hardcore interesting from the getgo