Mac Pro 2013 external hard drive expansion

For that use case, and asuming you have the black trashcan Mac Pro, you can simply plug them into the 4 USB ports and 6 thunderboll ports on the back.

You can use external docks or hubs with more USB ports or to convert the thunderbolt ports to USB ports if you wish, and yes these can be transferred to a new computer by unplugging them from the Mac Pro and pluggign them into the newer computer you get.

For example:

click here ➜ SABRENT 10-Port 60W Powered USB 3.0 Hub, Power Switches & LEDs (HB-**10) - Amazon.com

Apple offers their bi-drectional adapter so you can convert a thunderbolt 2 port into a more modern thunderbolt 3 / usb-c connector

https://www.apple.com/shop/product/myh93am/a/thunderbolt-3-usb%E2%80%91c-to-thunderbolt-2-adapter

Newer computers will have USB-C / Thunderbolt 3/4/5 rather than regular USB-A or thunderbolt 2 ports so you might need to consider adpaters when that time comes or newer USB-C hubs.

Outside of that, there is no special configuration required to attach mutiple external hard drives to the Mac Pro, you just plug them in wait for them to be accessible in Finder and you are off to the races.

The most prep you would need to do is if they aren't formatted for Mac as HFS+ or APFS already you would want to format them to that, preferably APFS so they keep working in future versions of macOS. HFS+ may not be supoprted for too much longer.

Economical Rotating Magnetic drives can easily be supported with the ports you have.

In fact, older USB-2 ports, which run at only 480 M bits/sec, provide an effective 48 M Bytes/sec potential data transfer speed. This is comparable to the maximum steady-state transfer rate of most Rotating Magnetic drives.

Yes, drive-makers may show specs that say their drives can support a first burst at up to 120 M Bytes/sec, but that is followed by an enormous dead-time while the head moves to the next track for more data. Effectively these drives run no faster steady-state than about 50 G bytes/sec, so having a bus at comparable speeds does not slow data transfer in a substantial way.

Early USB-3, like on the Mac Pro 2013, supports data transfer over ten times faster, at up to 5,000 M bits/sec, or 500 M Bytes/sec. Later Macs with modern USB-C ports support up to 10,000 M bits/sec, or 1,000 M Bytes/sec.

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And once you have that data in memory, getting it out to a Users has an additional impactful pinch-point. A very fast internet connection these days is 1,000 G bits/sec or 100 M Bytes/sec.

I recommend you NOT spend a lot of money on really fast drives and interfaces when your purpose is providing archival information.

Configure for what purpose exactly?

Beyond plugging them in and having them show up in Finder, what are you gonna be using them for?

How are you planning on connecting them? USB? Thunderbolt?

Give us some details and we may be able to advise, otherwise, we have no idea what you want or need.