I use Spacemacs (highly recommended) who's latest versions aren't compatible with earlier Emacs (eg, 25 is common on 18.04).

# Install Emacs 27
sudo add-apt-repository ppa:kelleyk/emacs
sudo apt update
sudo apt install emacs27

# Install Spacemacs
git clone https://github.com/syl20bnr/spacemacs ~/.emacs.d