Why not giornali ? In the UK we can refer to newspapers as dailies or weeklies so could we translate the sentence as " At three years old he reads the dailies"? This would translate one idiom into another.
does it make sense to use quotidiano? At thrrr years old he reads daily. Would that be correct?
"Daily" can be both an adjective (daily bread) and an adverb (eat daily); the former is "quotidiano" but the latter is "quotidianamente".
Yet again, a spot where making a guess based on previous usage of the word gets punished. There is no way to make that jump without either peeking at the word's meaning (which I don't do unless I'm stumped) or knowing a point of future grammar (that "daily" as an adverb takes a different form).
It would be better if that were introduced before a question is asked about it.
Publications can be referred to by their periodicity; a newspaper can be quotidiano (daily), a magazine can be settimanale (weekly), quindicinale (out every 15 days) or mensile (monthly).
I think it is also correct to write "At three years old he is reading newspapers". In English the present tense of 'to read' is: he reads, he does read and he is reading.