Totara Learning Solutions continues to support many versions of Totara Learn. As such developers will need to be able to run, develop against, and test under multiple versions of PHP.
How you achieve this is up to you, and your decision will likely be based around your operating system of choice, and how comfortable you are with the different options out there. Developers within the office already take a number of approaches, including using PHP-fpm and running on different ports, and docker.
The following are some documents written by developers in the office that may help you: