When setting up a WordPress site, it is helpful to determine the compatibilities of the technologies you are planning on using so that you do not run into issues later in your development. In particular, assure that the following components are compatible with each other:
- Theme version
- WordPress version. For example, you might not want the latest version.
- Plug-in version
- PHP version
- Database version
The above need to be compatible from the start. The below reference can help to assure that your WordPress components are compatible with your PHP selection:
For further planning and upgrades, here is a good reference:
https://wpastra.com/guides-and-tutorials/changing-wordpress-php-version/