I'm tired of the copied and pasted strategies I found online, which involve modifying system files to grant sudo privileges. It's ridiculous. In fact, it can be done in just three steps.
First, log in to the system with a user account that has sudo privileges:
Run the following command:
sudo su
Then, run the following command:
adduser new_username
You will be prompted to set a password, but you can simply press Enter to skip filling in the specific information.
Finally, run the following command:
usermod -aG sudo new_username
And you're done!