You want to look for a USB-C-to-HDMI or USB-C-to-DP adapter. It is best if it is also Thunderbolt 3 compatible. There are some that can support a 4K monitor at 60Hz.
If you ever want to connect two (or three) monitors, there are MST Hub-based adapters (like the one Al pointed you to) - but remember that, in this case, the monitors will be sharing the bandwidth of a single DP output stream. This means that two 4K monitors could be connected - but only at 30Hz. BTW, this same adapter is US$30 cheaper on Amazon: https://www.amazon.com/USB-C-HDMI-Adapter-Thunderbolt-Compatible/dp/B06XPVGQKY.