PageSpeed Insights error fixing (without using extra plugins) (Wordpress)

I want to fix a few errors on page speed insights for my WordPress website, knowing that the website is in production and can not be down for any time.

The target is as follows:
1- Get a score of 100% for accessibility for both (mobile & desktop)
2 - Fix "Core Web Vitals assessment: Failed" on mobile
3 - Make "First Contentful Paint (FCP)" in the green area for both (mobile & desktop)
4 - Make "Time to First Byte (TTFB)" in the green area for both (mobile & desktop)

Plugins installed for optimization are as follows:
1 - WP Rocket Premuim.
2 - EWWW image optimizer Premium.
3 - CDN is bunny CDN

Server Specs are as follows:

- VPS (Contabo) with cyberpanel (6 vCPU Cores, 16 GB RAM, NVME harddisk)

Terms and conditions:
1 - All requirements must be achieved.
2 - The website must not go offline.
3 - No used plugins should be deactivated.

URLs:

Page speed insights score: https://pagespeed.web.dev/analysis/https-keyhubstore-com/5rznqeyvzp?form_factor=mobile
Website: https://keyhubstore.com/

please write Hello Client at the beginning of your proposal to be considered.

PLEASE DO NOT TRY TO CONTACT ME VIA WEBSITE CHAT OR SOCIAL MEDIA OR YOU WILL BE REPORTED.

Thanks for understanding.