Try using another USB-C port especially on the other side of the laptop if you have the four port model. Try unplugging the charger from the electrical outlet for a minute to reset the charger's internal circuitry. You can also try rotating the charging cable connector 180 degrees upside down in case you have a half bad USB-C port. Disconnect all other external devices in case one of them is causing a problem.
Try an SMC Reset. Try running the Apple Diagnostics to see if any hardware issues are detected.
Even on the older Apple laptops it was common for a completely discharged battery from allowing the laptop to power on or even charge. These Apple USB-C laptops have some other very strange behaviors even when nothing appears to be wrong with them. I have seen the battery symbol prompting to connect a charger even though the battery has a significant charge.
See if your laptop qualifies for this free Apple battery repair program:
https://support.apple.com/13inch-macbookpro-battery-replacement
FYI, here is the current list of the publicly acknowledged free repair programs for various Apple products (some products like you laptop may have multiple programs):
https://support.apple.com/service-programs
