Website sections missing

Hey guys
Every time I install a theme on WordPress site, it shows several sections like slider section, services section, testimonial section. But I can’t see those sections on my site.
I can’t edit them or access them but only see them in the customization.
Do I need to download a template from the source website of the theme or do I need to install demo. I am a bit confused.

Can anyone help with this?
section 1