Plugging in your numbers, it's something like:
(1000(your attack) * (1 + 50%)(element damage bonus)*(500%(skill multiplier))*50%(same level between you and your enemy)*(1 - 10%(enemy resistance)) + 20.000*33%(Zhongli 4th ascension passive)) * 120%(crit damage modifier)
Not entirely sure yet if the 4th ascension passive is before the crit, but the result is roughly around 7425.
