Where does Google Chrome automatically save pages? I opened the following page: https://goughlui.com/2014/10/01/usb-cable-resistance-why-your-phonetablet-might-be-charging-slow/

When disconnecting WiFi and even after rebooting the mobile phone, the page can still be read due to being saved automatically.

Left to the URL bar, an indicator looks like this:

This also shows up when opening manually saved pages, which are saved as MHTML files in the default download folder.

However, an automatically saved page can not be re-downloaded manually to get to the download folder, because the arrow is greyed out.I wish to copy some automatically saved pages into the download folder.

Where are the files of automatically saved pages stored?
This would be in Chrome data, which means you need root and on my device running 8.1 stock this seems to be it

/data/data/com.android.chrome/app_chrome/Default/Offline Pages/archives/ where you have .db (databases)

In one of the databases prefech_store, I could see the information pertaining to off-line pages

This may not help you as HTML/MHTML pages are not available directly for your purpose (searching for those in the app data didn't turn up any which implies they are stored in databases only)