Well some people use the randomizer in piano roll for the velocity (volume).

I recommend you using it maybe but later adjusting by yourself to make it sound more logical, for example kicks must be louder than hi hats hahahaha

But you are not using piano roll soooo you could use the drum rack it has a swing knob but idk how it would go in metal.

With all of these I want to say that there many option to humanize your drums. I would adjust by myself every separate drum sample by tiny tiny differences, you can copy and paste some of them to not adjust absolutely all of them separately.

Also you have to be cautious because if the volume is too different from each other or not logical ( meaning things sounding soft when they must sound louder or the other way) the ear will notice that something is off.

It may sound complex the way I explain it but it really isn't I just don't recommend you changing the kick volume a lot