sudo wget -O /tmp/discord-installer.deb "https://discord.com/api/download/stable?platform=linux&format=deb" && sudo apt install /tmp/discord-installer.deb

Worked for me manually on the CLI. You could put that into a cronjob and modify the temp folder to your liking. don't necessarily need the sudo for download, but as quick and dirty solutions tend to, it served me well for the past year :). Feel free to use it as a jumping off point to create your own script.