First you will need to open a terminal and install rar/unrar.
sudo apt install rar unrar
Then you can navigate to the directory to where your .rar file is. Typically, the file name you are looking for is the first in the numerical sequence. Example: “sample-001.rar”. You will see “sample-002.rar”, “sample-003.rar” etc.
Unrar into the current directory:
sudo unrar x sample-001.rar
Unrar into another folder or drive:
sudo unrar x -e sample-001.rar /media/usb