Yes, you can do that using anchor links.
https://hc.weebly.com/hc/en-us/articles/203905186-Create-Anchor-Links
Follow that guide to create anchors on your pages, then add links to your navigation using the external link option with this format:
http://www.mysite.com/index.html#myanchor
Make sure to replace "www.mysite.com" with your site address, and "myanchor" with whatever the name of the anchor is you want to link to.
