Install the latest version of Ruby, Rails, Postgresql, Yarn, Webpacker

rails -v
ruby -v
rvm list
rvm get head
rvm install ruby-3.0.1
rvm --default use 3.0.1
rvm uninstall 2.7.3
gem install rails -v 6.1.4
gem install rails -v 7.0.0.alpha2 
gem update rails
gem update --system
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
sudo apt update
sudo apt install postgresql libpq-dev redis-server redis-tools yarn
ruby -v
rails -v
pg_config --version

Next Step - install Postgresql

Oldschool? Try to install Ruby on Rails 5