Improve Website Speed for Wix Website

Looking for an expert to help improve website loading speed for a Wix website. Currently, website is rated:

Website: www.plrebooksupplier.com

Performance is 21 for Mobile:
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First Contentful Paint 2.8 s
Time to Interactive 22.9 s
Speed Index 13.1 s
Total Blocking Time 3,690 ms
Largest Contentful Paint 20.5 s
Cumulative Layout Shift 0

Performance is 52 for Desktop:
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First Contentful Paint 0.7 s
Time to Interactive 4.9 s
Speed Index 2.9 s
Total Blocking Time 830 ms
Largest Contentful Paint 1.9 s
Cumulative Layout Shift 0

Here is the full report:

https://pagespeed.web.dev/report?url=https%3A%2F%2Fwww.plrebooksupplier.com%2F&form_factor=desktop

Wix Tips for Improving Website Speed:
https://www.wixseoexpert.com/post/tips-to-improve-wix-loading-speed

Anything else you can recommend and help me with is much appreciated. If you give me your proposal and cost, I will gladly consider. In your proposal, tell me:

1. Recommended steps you will take to improve site speed.
2. Your estimated performance improvement (e.g. I can guarantee you a 50% improvement)
3. Cost of project