Integrating Another Site Into My Main Site

Both sites don’t look like WordPress built sites to me. Am I wrong or why do you ask here?

apologies, https://www.thisisautomata.com is a wordpress site once you get past the entrance page. https://www.thisisautomata.com/blog/ is the address for wordpress portion.

And https://www.thisisautomata.bandcamp.com redirects to https://music.thisisautomata.com/

That said you could try this plugin https://www.ads-software.com/extend/plugins/embed-iframe/
allthough it is not updated recently.

In general, your question is the same as mine, when I was transforming my html site to WP. In the end I got rid of that type of solutions and made everything work directly within WordPress, because I found it easier to do all jobs in only one environment. Istead of doing job A in WP, job B in Frontpage and job C in Dreamweaver or whatever.