I run a small hosting company, and have little to no experience with Wordpress myself. It's just something I offer clients.

I have one client that had a WP site built on a custom theme, using WP version 4.7.29. They also have these plugins:

Advanced Custom Fields 4.4.5
Contact Form 7 3.8.1
Document Gallery 2.3.7
Google Analytics for WordPress 4.3.5
NextScripts: Social Networks Auto-Poster 3.7.15
SSL Insecure Content Fixer 2.5.0
WP Realtime Sitemap 1.5.4
WordPress Importer 0.6.1

I'm removing the server that they're on, so I need to move them to a new one with PHP 8.4. I'm assuming that I'll have to install WP 7.0.2, too.

I CAN pay a monthly fee to install PHP 7.4 again, but is there a way to install the old WP version, too?

If not, any guesses on whether the old site will work properly with the updated software? How can I know other than "try it and see" (and risk breaking everything)?