One image in thumbnail share

Hi all,

I use a theme that has no images other than my site logo. When I share a post on social media, it uses the logo image which doesn’t look great. Is there a way to use one image that is used when sharing the link?

I have an image I’d like to use so whenever I share a post or page the thumbnail is the same.

If any one can point me in the right direction, that would be awesome!

Thanks,
Ben