Hi
If you want to completely change the demo version of the site, it is recommended to run import on fresh WordPress installation https://wordpress.org/plugins/wordpress-database-reset/ If you want to import sections from different demos, use XStore studio. Just edit page using Elementor > click here – https://prnt.sc/udpfle and import the desired block.
Please read our documentation – https://xstore.helpscoutdocs.com/article/34-demo-content
Let us know if you need any further assistance.