Yes, the noun pair is a collective noun, a word for a group of two:
The collective noun for shoes is a pair.
The collective noun is a pair of twins.
The collective noun is a pair of tights.
The collective noun is a pair of hands.
The collective noun is a pair of rubbers.
The collective noun for shoes is a pair.
The collective noun is a pair of hands.
The collective noun is a pair of twins.
The collective noun is a pair of tights.
The collective noun is a pair of shoelaces.
The collective noun is a pair of rubbers.
The collective noun for earrings is a pair of earrings.
The collective noun of boots is a pair of boots.
The collective noun is a pair of prescription glasses.
The collective noun for 'socks' is a pair of socks. There is no standard collective noun for a larger quantity of socks. A collective noun is an informal part of language, any noun suitable for the situation can function as a collective noun; for example, 'a load of socks', 'a bundle of socks', or perhaps 'a crew of socks'.
There is no standard collective noun for rainbows.A collective noun is a noun used to group people or things. Rainbows don't normally form in groups.Occasionally, a double rainbow appears. You could use the noun 'pair' as a collective noun: a pair of rainbows.
There is no standard collective noun for a group of bangles. However, collective nouns are an informal part of language. Any noun that suits the context can function as a collective noun; for example, a pair of bangles, a row of bangles, a jingle of bangles, etc.