How to expand to external storage on a Mac Studio

You can use an external ssd. I have a Thunderbolt External drive and keep my movie folder on that drive. All I did was moved from internal drive to external ssd. I saved 89gb of space. You can do the same with Photos etc.

<< I suspect they would need to be stored in the primary internal SSD. >>

Only system files need to be stored on the boot drive. EVERYTHING in your User folder and anything else can be stored on an External drive of any description.

and if you want to bad enough, you can use an external drive as a boot drive.

Newest SSD drives on the market are claiming one drive at 7,000 Mbytes/sec.

So RAID is no longer a requirement.

Thunderbolt connection is the bottleneck that limits you to just around 2,700 M bytes/sec, so don't pay extra for claims of faster.

The problem is that all the 7,000 Mbytes/sec are NVMe and NVMe

drives are more expensive than 2.5” SSDs and not available in larger sizes.

If you want faster 8 or 16tb then RAID is about the only

choice.

Most 40Gbps NVMe enclosures have pretty decent heat sinks

but it varies. I like Orico but there’s a lot of choices out there.

I connected my new Mac Studio to a Thunderbolt3 OWC with 4 SSD enclosed and I get in RAID 0 to 1000-1200 MB/SEC (write-read). I'd recommend you have a look to Th3 SSD devices

As others have said an external RAID SSD works pretty good

If you need more speed a fast NVMe in a fast Thunderbolt 3 enclosure can get you 2.7GB/s

https://www.netapp.com/data-storage/nvme/what-is-nvme/