Try an SMC Reset.
Connect the charger directly to the laptop. Connecting the charger to a multi-port adapter, dock, or hub may not allow the full power of the charger to reach the laptop.
Also make sure you are using the correct charger for your laptop. Using too small of a charger will cause the battery to drain in order to compensate for the too small charger. Try using another USB-C port especially on the other side of the laptop if you have four USB-C ports. Try rotating the charging cable 180 degrees upside down as well (I know this sounds crazy, but it can make a difference if there is a hardware issue).
Disconnect all external devices from the laptop in case they are causing a problem.