You can add as many pages as you wish to your atlas and design each accordingly to your need. If you want to have a first page with the title and a second page with an overview map (not controlled by atlas) and starting from page 3 your atlas, just add a first page with text only and a second page with a new map element. Here, just don't activate the "controlled by atlas" checkbox. Than add a third page with a new map, this time check "controlled by atlas".
If you export your atlas, however, the first two pages will be exported for each atlas item separately - if you have 70 features in the covering layer for your atlas, page 1 to 3 will be output each 70 times, thus 210 pages. That is not what you want: you want page 1 and 2 just once, page 3 instead should generate the 70 atlas pages, thus in total 72 pages. To achieve this, do the following for page 1 and 2: open page item properties panel (right-click on your page) and check "Exclude page from exports". Thus, your pages 1 and 2 won't be exported at all. You have to define a condition in such a way that those pages are exported just once - for expample for the first atlas feature, but not for all subsequent features (2 to 70). In the data driven override insert the expression @atlas_featurenumber <>1 that does exactely this: the variable @atlas_featurenumber refers to the respective atlas feature that is output, thus: if the feature is not (unequal: <>) 1 (thus it is 2, 3, 4, ... 69 or 70), the page is excluded from export. In all other cases (thus: if the atlas feature is equal to 1, thus for the first iteration only), the page is exported.
In a similar way you can define page numbers: add a text field and insert the variable @layout_page as page number. Probably, the title page (no. 1) should not get a page-no, pagination should start on page 2 with your overview-map (no. 2). Thus just insert the expression [% @layout_page -1%] to have page 2 numbered as page 1. Starting with page 3, you have to slightly modify this as now the page number should increase with each atlas-page you output, but starting not with one, but with 2 for the first atlas page (because page 1 is the static page with your overview map). Thus the expression to achieve this is: [% @atlas_featurenumber +1%]
Like this, you could add many more static pages and define each page in a different way. However, my experience shows that the print layout will get very slow with a few pages and many tweakings as described above. So in each case evaluate if it would be better to design title-pages, table of contents etc. separately, manybe even in a stand alone software where you have more control over text-layout. But technically, QGIS print layout is extremely powerful and with a little bit of work, you can achieve (almost) everything.
See documentation here: https://docs.qgis.org/3.10/en/docs/user_manual/print_composer/create_output.html#generate-an-atlas
