Not sure I understand your question.

I've looked up about the Focusrite 8i6, and I've noted the spec, the pics, and seen some description about it.

I note the box has, amongst other connectors, a midi in and a midi out. I see no sign of a separate thru.

The 'blurb' says that the device has all the connectors required, and therefore no need for any 'break-out' cables, which in this context would mean - I believe - the provision of required connectors (for whatever) via external cable with the extra connector(s) on the end.

A midi thru is handy, but is not essential. It is usually implemented as an OUT which is connected immediately to the IN, so that any IN signal is passed on without any processing to other units, making daisy-chaining of devices more efficient.

A 'break-out box' could provide ANY sort of connector, depending on the device being broken out of. In the context of the 8i6, a 'midi breakout box' would provide extra midi connectors (more IN, more OUT, or evev one or more THRU), although the pics I've seen do not show any provided connector for such an extension.

Geoff