How do you do your featured image designs?

So I'm running an amazon affiliate blog, but I have no idea what to do for designs for the featured images.

Do I use the same design template for every featured image? Or a different design for every post?

Any designers have any tips? I have reviews and informational articles.

It really depends on how your theme has the featured images shown.

For one of my sites i just have plain images because my theme writes over it with details like the post title. But another site I have a design where I just the background image and the text for the featured image.

I appreciate that doesn't help massively

I use canva, Yes I have a template on which I place a transparent image related to article. And change the colors and title as required

Same template with swapped colors would do.