First decide whether you need a Cloud Server
If a standard hosting environment supports the site, Web Hosting can remove unnecessary server administration. Choose a Cloud Server when you need dedicated resources, custom services, a specific deployment process or operating-system control.
CPU affects dynamic work
PHP execution, uncached requests, image processing, background jobs and database work all consume CPU. Traffic volume matters, but the percentage of requests that can be cached is equally important.
RAM provides working headroom
Memory is shared by the operating system, web server, PHP workers, database, cache services and other processes. Size for simultaneous activity rather than the memory limit of one PHP request.
Storage is capacity and behaviour
Estimate the operating system, site files, database, logs and media growth separately. If application data is expected to grow, separate Cloud Storage can make capacity planning cleaner.
Leave room to observe and adjust
Start with a reasonable configuration, measure real resource use and resize when the evidence supports it. Avoid both extreme undersizing and paying indefinitely for resources the site never uses.