Try using another USB-C port. Try one on the other side as well if you have four ports. Make sure you are using the proper USB-C charging cable -- not all cables may charge the laptop. Make sure to plug the charging cable directly into the laptop since some dongles/docks may have issues. Also make sure to unplug the charger from the electrical outlet for a minute to reset the charger's internal circuitry. Also try an electrical outlet in another room.
See if your computer qualifies for this free Apple battery repair program:
https://support.apple.com/13inch-macbookpro-battery-replacement
Here is an Apple article for troubleshooting USB-C charging issues:
https://support.apple.com/en-au/HT204652
FYI, here is a list of all the current publicly acknowledged free repair programs for various Apple products (some products such as your laptop have multiple repair programs):
https://support.apple.com/exchange_repair
If this doesn't help you, then you will need to get the laptop repaired.