Core Web Vitals - Fix "Reduce initial server response time"

I have a Wordpress website hosted on CentOS VPS server.
My core web vitals show the following issue: Reduce initial server response time
I need someone to fix this issue.
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WordPress Website
Hosting on Linode VPS
OS: CentOS Linux release 7.9.2009 (Core)
Web Server: Apache
PHP: PHP 7.3.33
Performance Plugin: WP Rocket
SEO Plugin: Yoast
CDN: Amazon CloudFront

NO EXPERIMENTING. APPLY ONLY IF YOU KNOW HOW TO FIX THIS.

Thanks