It includes attractive and high quality images in content, especially if they are large, since they are more likely to generate discover visits. Large images must have at least 1200 pixels wide and must be implemented with the max-image-preview adjustment: Large or by AMP."

Actually what I need is that the images 960 x auto are 1200 x auto. How can I change it at the CSS

I think I have not explained well. We already use a plugin for this, but I need the outstanding post image of 1200 px wide that is how we upload it for discover. But since the width of the column of the text is less the scale. I think that's why there is a longer LCP time. The fact is that the template in modifying the width of the text area does not work correctly and I cannot make the 1200 px or more measure to show the image without scarge

In pagespeed it tells me this. I think it may be because the outstanding image we put is 1200 x 728 but the post of the post is lower and the template does not let me modify the width.