Step 1: Login to the Plesk panel with your admin login credentials.
Step 2: Click the Tools and Settings section.
Step 3: Under the Plesk section, select the updates and upgrades option.
Step 4: Then click Add/Remove Components to install the multiple PHP versions.
Step 5: Under the Web Hosting Feature, select the ‘Different PHP interpreter versions’ and then select the PHP versions that you want to install in your Plesk.
Step 6: Click Continue to start the installation process. The PHP versions are available once the installation process has been completed