Shopify LCP Optimization

My Shopify website currently has a Largest Contentful Paint (LCP) of 4 seconds. I have already optimized the images on the front page to smaller sizes but am still not seeing much difference.

I need help in reducing the LCP.

Requirements:
- Analyze and optimize LCP elements.
- Improve loading speed significantly.

Ideal skills and experience:
- Expertise in Shopify speed optimization.
- Proficiency in image formats (JPEG, PNG, WebP).
- Experience with lazy loading implementation.

Please provide a detailed plan and timeline.