Formatting at Samsung T7

What happens when attempting this in Disk Utilities. Disk Utilities >> View >> View all attached devices >> Let side Choose the Upper most Samsung Named Device. Partition it as single and Format as APFS below that Scheme: GUID Partition Map and Erase giving it a preferred name

Is this disk an external SSD or the internal boot drive for your Mini?

What happens when you try to erase it with Disk Utility?

If it's the boot drive you must boot into the Recovery volume (boot with the Command + R keys held down) and do the erasing with Disk Utility from there.

I think the APFS option will appear if repartitioned

What exact model T7 is it? Why do you need to format it APFS? If you're just going to use it for a data disk I'd leave it at the OS X Extended (journaled). I have several external SSDs for data disks and all are OS X Extended (journaled). They've been running find for quite a while now.

Did you do what P. Phillips suggested regarding Disk Utility?