GNU/Linux Mint Realtek rtl8723be Driver Installation Guide
Hi! The linked Tutorial shows you Step-by-Step How to Install Realtek rtl8723be Wireless Driver in Mint 19.x/20.x/21.x LTS GNU/Linux.
The Realtek rtl8723be Linux Mint Driver should be already bundled into the Linux Kernel.
But if needed as a replacement see the Realtek rtl8821CE/rtl8192CE Driver Setup.
Installing Realtek rtl8723BE Driver in Mint