usermod -aG sudo username
# add a user and set a password
adduser USERNAME
# add user to sudoers / sudo groupe with command below
usermod -aG sudo USERNAME
sudo grep -B1 -i '^%sudo' /etc/sudoers
# Allow members of group sudo to execute any command
#%sudo ALL=(ALL:ALL) ALL
sudo adduser <UserNameHere> sudo
or
sudo usermod -aG sudo <UserNAmeHere>
id <UserNAmeHere>