Linux

Warning: this is definitively doable, but messier than it looks like. I'd recommend you to partition it manually, before installing any distro, like this:

• one partition per distro. For sizes check their requirements. Given 500GB I'd probably reserve 60GB for each, perhaps a bit more if I know that I'll install a lot of stuff in that distro.
• one swap partition, that'll be accessed across distros. Optional if you have 16GB+ of RAM.
• use the leftover space for a "storage" partition, for personal files that you won't save in someone else's computer (i.e. the cloud). That allows you to mess with the distros without risking your personal files.

Don't worry too much on getting the space right though - if necessary you can always resize a few partitions after installation. It's a bit of a bother though.

Do not share /home across distros, it's simply more trouble than it's worth. Instead, mount that "storage" partition in each distro, inside your /home/[$username] directory.

Another thing that you might want to consider is virtualisation. Odds are that you won't use a lot of those distros in your everyday, and that you're just curious about their differences. In that case, consider installing one of them, install Virtualbox in it, and then the other distros get installed inside Virtualbox. I'm suggesting that because it'll use overall less space, and make distro management less messy.

Have you tried distrobox ? That would sound more reasonable.

So Question: What do you actually want to achieve?

Do you want a rolling, semi-rolling or stable releases? More tested or even LTS packages, or the latest?

So... I guess it should work but you will end up with looots of partitions and pretty sure you have no idea what is what.

But if you plan on nuking it in the end, here is how to do it:

• install a Distro to full hard drive
• use some partition manager like KDE-Partitionmanager (the best of all) or Gparted and resize the big ext4/btrfs/zfs whatever storage partition as small as you want
• install the next distro into the empty space
• shrink that distros storage again, repeat

And please report if some crazy stuff happens with Grub or if you get secureboot working!

Not an answer to your question, but have you checked out Bedrock Linux as opposed to installing multiple distros? Or maybe using virtual machines?

One thing that might matter is that if all distros use the same swap partition for hibernation, you shouldn't boot one distro after hibernating another or you might overwrite the saved RAM contents.

If you use different swap partitions or files, you probably should still avoid writing to a partition that belongs to a distro that isn't actually shut down.

Why?

Triple booting is a pita, moreso if you don't know how to partition a disk. I'd want any laptop encrypted, which adds further complexity to the triple boot.

If you wanna browse, research, watch videos and tinker just install a distro. If you wanna spend time switching your system off and on again over and over and over again to find out what's working/broken go for the triple boot.

Docker could be worth a shot. You can 'docker pull fedora/arch/debina/whatever' and can play around with the base systems. Alpine takes up about 6mib so isn't too resource intensive if you need to nuke it a few hundred times to get up and running.

All these people saying don't do it - clearly, they're trying to learn something and are not necessarily after a fully usable, encrypted production system. Instead of telling them it's too complicated, we should encourage to play around and figure it out, so in the process maybe they find out on their own why this configuration might not make any sense in most situations.

So @op, just go for it, you're going to learn a lot from this!

Perhaps consider watching this excellent video guide on dualbooting and multibooting by DorianDotSlash. It was what I used as a reference the first few times I engaged in dualbooting and/or multibooting.

It could be done if you partition your disk prior to installing but, if there is no particular reason, you could make a bunch of VM's and daily drive one of the distros.