LCP or Largest Contentful Paint is the core web vitals considered by Google to measure the website's performance, which basically tells how long the main content on the website takes to load on the webpage.
You can improve LCP by:
Compress the images to reduce their loading time
Utilize CDN (Content Delivery Network) to reduce the distance between server and user browsers
Implement AMP (Accelerated Mobile Pages) to allow Google to store cached versions of the pages on mobile servers and reduce the loading time of the images on mobile devices
Enable browser caching to preload the website resources
Implement lazy loading for advertisements and large images