How can I make my Realtek RTL8821CE wireless hardware work?

You have Realtek RTL8821CE hardware, so use the following steps:

Open up a terminal by pressing Ctrl+Alt+T and type:

cd /tmp/
sudo apt install --reinstall git dkms build-essential linux-headers-$(uname -r)
git clone https://github.com/tomaspinho/rtl8821ce
cd rtl8821ce
chmod +x dkms-install.sh
chmod +x dkms-remove.sh
sudo ./dkms-install.sh

Which will download the Arch source and build the driver. After the above is completed, you can insmod the driver or simply reboot.

Warning: As you're downloading and building your own driver, ensure SecureBoot is disabled in the UEFI Firmware / BIOS if a simple reboot would not bring the desired result.

This is available as an apt package on 20.04 - Run: sudo apt install rtl8821ce-dkms, restart and you're done :)