Refers to the extent, magnitude, or amount of something, often used in formal or written contexts. Can imply both large and small degrees.
The extent of the damage is still unknown.
Regardless of the amount of income, saving is important.
Regardless of the amount donated, we send a thank-you letter with our gratitude.
This is a course anyone can join, regardless of how much experience they have.
The evaluation largely depends on the amount of results achieved.
量 simply denotes 'quantity' without implying comparison, whereas 多寡 emphasizes whether that quantity is large or small.
多少 is a more colloquial way to express 'amount, more or less', while 多寡 is reserved for formal or written contexts such as 多寡を問わず.
Compound of 多 (ta, 'many') and 寡 (ka, 'few'), literally meaning 'many or few', extended to refer to the degree or amount of something.