'Hit on someone' means like 'flirt with someone'. Then when I wanna make the tone stronger, can i put 'up' like

Hit up on someone

is it ok in american english, or british english?

or it would be ok but as a native(american or english), almost no one say 'hit up on someone'? 99% says 'hit on someone' only?

Thanks teachers:)

"Hit on" means to flirt. "Hit up" means to initiate contact. "Hit up on someone" is not something people say.

You could say "coming on" to someone, which is a bit more sexual than "hitting on". "Courting" is a more formal process of flirting and dating with the purpose of marriage.

There are three idiomatic phrasal verbs:

1. hit on - meaning to flirt : "John fancied Susan the moment he saw her, so he hit on her."

2. hit up - meaning to request (someone) to do or give something : "John hit me up for more money."

3. hit upon - meaning to mention or address; to suddenly have an idea; to discover something by chance : John will hopefully hit upon all of the customers' concerns during the meeting.

Your suggested usage of "hit up on" isn't idiomatic. It is not an emphatic version of "hit on." I don't see anyone inferring that meaning from the words themselves.