change default size of featured image on single posts page

Hi there,

if its a default install of GP then you can use the Customizer > Layout > Blog:

https://docs.generatepress.com/article/adjusting-the-featured-images/

There you have Archive, Post and Pages tabs where you set the Media Attachment size of the Featured Image

If its on a site that was imported from a site library then i would need to see the site.

Hi,
It is the MyPet, a site that was imported from a site library.
Please have a look at it, thanks.
I made custom posts that link from the "Aktuelles" section on the bottom of the home page to the single custom posts. On these, I want the featured image smaller.
Thanks.

I'm not sure which image are you referring to, do you mean this image banner?
https://www.screencast.com/t/vWLe1LhWGJKu

If so, these are not featured images.

Or do you mean this?
https://www.screencast.com/t/kSYyLrdJ

If so, how would you like it to be smaller? I can not see a way to make it smaller and look great, can you show us a mockup?

Hi, I followed David's advice and changed the featured image size in use the Customizer > Layout > Blog.
That worked.

Is there a way to make default rounded corners for the featured image?

Thanks
Mel

It requires some CSS, and depending on how the featured image is displayed will affect that CSS.
Can i see a post with the image ?

Thanks, David for the reply. The link to the Post with the image is
https://www.hundetraining-mit-roya.at/staging/aktuelles/lernspaziergang/

I also would like rounded corners for the featured image in New Pages. Here is a Page with a featured image:
https://www.hundetraining-mit-roya.at/staging/new-test-page/

Both these pages need login to view, please see details in the Private Information field.

Try this CSS:

.featured-image  img {
    border-radius: 10px;
    overflow: hidden;
}

That's great, it worked.
Thanks very much!

Glad to hear that!