How to improve my First Contentful Paint (FCP) and Largest Contentful Paint (LCP)

Question

I'm struggling with my first Wordpress website I bought over via Flippa.

The website used to generate thousands of visits. Since I took over, the performance has decreased and the Google Ranks went from 1 to 10+...

The main issue so far that I can see is the page speed performance

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It takes 5.1s to load on mobile - which is a no-go for Google. Here's the page for example: https://citydogslife.com/best-medium-sized-dog-breeds-for-apartment-living/

The main issues are the FCP & LCP:

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However, I have no clue on how to fix those. Clearly didn't change anything on the files but PageSpeed recommends all these without concrete actions.

Is there anyone who has experience on how to fix the LCP and some of these other points?

Thanks!

Appreciate anyone's help.

1. I tried to remove Ezoic - the page speed increased slightly but not so much.

2. I tried to re-upload the same website transfer files given by the seller twice but the speed still does not improve.

3. I optimized all images on the website 3 times with different providers to ensure their sizes were not huge