No. I learned how to do that (iframes) in the 90’s.
What I mean is if you create three pages called A.htm, B.htm, and C.htm, and then you create another html page, like index.htm, and when index.htm opens, all anyone can see are the three pages in a row at the dimensions specified in index.htm.
The three pages can be horizontally aligned or vertically aligned.
And, you can do the same with pages A, B, and C. You could create A so that when it opens all you see is D and E.
That means if you created A, B, and C to be side by side instead of above or below each other, then you could create D and E to appear in the spot designated for A with D on top of E.
It also means it’s impossible for anyone to view the page source of index because when they put their cursor on A, B or C, the can only see the page source of A, B or C.
And, if A is used to display other pages in it’s place, it means you cannot view the page source of A either, but you can view the page source of the pages appearing in the place of A.
And, if you code the pages to have no scroll bars, the final viewing result, no matter how many different pages (I have done nine pages) all appear with no edges as if one page.
So, for example, you could have a banner ad page across the top, a home page in the centre, and a page for links like home, menu, about, contact, going across the bottom, with all links on any of those three pages opening either in the centre (so that the menu bar at the bottom stays visible permanently and the banner ad stays visible permanently, but the home page changes with whichever link is clicked, and you can always return to the home page through the home link at the bottom which is permanently visible while at the site.