Do this on your local or virtual enviroment, depending where do you want to have it
mkdir ~/drush10 cd ~/drush10 composer require "drush/drush:10.*"
this will install drush10 to that directory and now you just need to add alias
and from now on drush10 will call drush 10.x version and regular drush will call default one, add like this more versions if you need.