Loading lazy background CSS?

I’ve searched several times, but haven’t found an answer.
Is it possible to inform in the CSS below the lazy loading for the image?
If so, I kindly ask friends to help me.

.testimonials {
  padding: 80px 0;
  /*background: url("clientes/criacao-de-site.webp") no-repeat;*/
  background-position: center center;
  background-size: cover;
  position: relative;

You can do it with the Intersection Observer API

have a look here

Unfortunately it broke the site, it worked, but it broke the site.
Thank you very much.

You can use lazy attribute in the html for lazy loading image or if u need something different or more complex u can use observables(as Kuliga have mentioned)