climb 1 /klaɪm/ ●●● W2 verb 1 MOVE UP/DOWN [intransitive always + adverb/preposition, transitive] to move up, down, or across something using your feet and hands, especially when this is difficult to do
Harry climbed the stairs.
Boys were climbing trees along the river bank.
climb up/down/along etc
The wall is too high to climb over.
They climbed up into the loft of the old barn.
so, "climb"is both intransitive & transitive.
When we say "the child climbed up the chair", then "up" is an adverb and "the chair" is the direct object of the transitive verb "climb"
When we say "the child climbed up onto the chair", then "up" is an adverb and "the chair" is the direct object of the preposition "onto" while "climb" is an intransitive verb.
are they roughly similar? "the child climbed up the chair" & "the child climbed up onto the chair"?
and Which one sounds better?