WordPress Developer for SiteGround

I am looking for an experienced WordPress developer to resolve technical and security issues on an established membership website hosted on SiteGround. The site currently runs PHP 7.4.34, which is outdated and unsupported, and previous upgrade attempts have caused the site to crash. One compatibility issue involving an outdated OptimizePress plugin has already been partially addressed, but additional problems remain. I need someone who can identify the remaining issues, successfully upgrade PHP, and ensure the website continues functioning correctly.