He doesn't have a real goal in life at all because he was a timid 14 year old who was taken to the abyss, trained and be told he has meant to be the eye of the storm everywhere he went + being given an abyssal transformation, then taken to the military where he was indoctrinated to be the Tsaritsa's weapon of war.
He loves fighting but has no desire to hurt civilians, loves children, wants his family safety over all and had to make sure Rex Lapis was actually alive before even thinking of hurting Liyue Harbor and a large list of situations where he has proven the idea of hurting anyone who wouldn't stand a fair combat.
If you think one line about 'one day conquering the world' is a good way to sum up a whole character then I don't have anything else to tell you, you are simply an illiterate idiot.
Also if you really like Arlecchino you should be at least aware that she actually likes Childe and, unlike Dottore who does have general dark intentions, is aware Childe doesn't have any, she knows he's young and inexperienced and wants the best of people.