голова (размером) в несколько футов

the original post makes no sense whatsoever

E.g. "they dug out its few feet head" - would this be incorrect?

Absolutely

Why is, say, "2 Feet Suitcase Ramp" correct then?
https://www.amazon.com/EZ-ACCESS-Feet-Suitcase-Advantage-Pounds/dp/B0010FKH66

Actually, it isn't correct. It should be "two-foot." Whenever we use quantities as adjectives, they always have a hyphen, and the second element is always singular because adjectives in English are never pluralized. That's why we say "the poor, the rich, the sick, etc." Aside from this, the first element has to be numerical, so FEW doesn't work. You can't say "a few-foot ramp" for example.

Anytime :)

OK, thank you
Does it have to be 'a few feet long/big head' then?

It should be a head measuring a few feet