The kind of scream you might do in fear or anger doesn’t work exactly the same as when it’s done in a controlled way.

The answers already present cover how to scream as a vocal technique way better than I could (I can only growl, I’ve never managed to get a proper metal scream). But the kind of scream that you make involuntarily tends to be made by the vocal cords being stretched tight. You can’t scream like that in a sustained way without it hurting. Too much air pressure being pushed through very taut cords, it just isn’t healthy. It’s also more of a head/throat generated sound and will be higher pitched.

If you want some awesome insight into the various vocal techniques used in metal, there’s a YouTube channel called “the charismatic voice”. The lady that does the channel is an opera singer that has turned into a metal fan, and is now doing research with a university. They recently did some amazing work with the vocalist Will Ramos, from lorna shore. MRIs, electric readings, cameras, etc. They’re building a body of research into “harsh” vocals.

But the channel as a whole, she’s watching/listening to videos of music, with it leaning heavily into metal. She talks about the mechanics of how the vocalists do it, and she goes in depth.

With that said, what you were doing, trying to yell for your friend to get their attention, that’s more projecting your voice. When you pull the air in deep, and push from the stomach up, using your body to support that push, you can be very loud with zero distortion. Volume of the voice is all about moving air efficiently. Ever see a movie or show with a drill sergeant barking orders across a big group of soldiers? That’s projection. It’s the same basic techniques that opera singers and stage actors use. It’s all about the air and the way you use the diaphragm with your entire body.

Anyway, some links

The channel I mentioned

The footage with the research

Some loud vocalizations that aren’t distorted but are musical

A quickie tutorial on the basic technique of growling

And one for the fry scream

That growl technique is essentially the same as the way I learned to growl (though I’m not very good at it), and it matches one another user described in text.

But, no bullshit, if you’re projecting your voice that clearly a block away, that’s fucking legit power. I can’t sing for shit, just can’t hold notes steady enough to be enjoyed by other people. But I tried. Getting to the point of being able to project my speaking voice clearly over a distance took months of work. So, if you can do that, you can absolutely learn to metal scream/growl, and likely be good at it.