If you are positive that none of the PC components were touched by the liquid, then it should not be any harm done.
The immediately danger of it is the ability to conduct electricity.
After that, other issues could arise...besides water, that type of drink contains sugar, acids and many chemicals that could corrode metals and create conductive path for electricity.
Cleaning sugary drinks from computer components like a motherboard is not an easy task, since little drops could find their way into sockets, fans, etc.
A small drop could eventually slow down
In similar cases I instruct the user to power off, turn off PSU, unplug power cord and remove the CMOS battery.
Then I disassemble an entire computer and use a non-conductive material microfiber towel to absorb the liquid. If the liquid is already drying, damp the microfiber towel with rubbing alcohol
and wipe all components affected as clean as possible.
Memory and PCIe sockets could be clean with
electrical cleaner.
A leave it to dry for a couple of days and hope for the best.