By default, comments are disabled on pages in WordPress. To enable comments, follow these steps in your WordPress Dashboard:
Go to the page where you want to enable comments.
In the right sidebar, locate the "Discussion" option.
Tick the checkbox labeled "Allow Comments" to enable comments for that specific page.
And make sure you have Show comments on pages enabled in the WordPress Dashboard > Divi > Theme Options > Layout > Single Page Layout > Enabled.
Now you should see the comments on your regular WordPress pages.
Another scenario: If you have the Classic Editor plugin activated or if you have the Classic Editor enabled from WordPress Dashboard > Divi > Theme Options > Builder > Advanced option, then the discussion option will look something related to the following screenshot:
And if you don't see the Discussion tab, you will need to enable it from the Screen Options of the top right on the edit screen and check the Discussion checkbox:
Important: If you use Divi Builder on any page, then having those options enabled is not enough. You will need to add a new module called Comments to the bottom of your page to show a comment form.
The visual builder will show something like the following screenshot:
And the preview will look something like the following screenshot when you see it on a page where you are not logged in to the site.