How to update MacBook Pro 2015 early from macOS Sierra to Monterey?

Here is an Apple article with links to the various macOS installers:

How to download and install macOS - Apple Support

You should also be able to access Internet Recovery Mode using Command + Option + R to access the online macOS 12.x Monterey installer. Sometimes even this key combination will still cause the Mac to boot into the older online installer for the version of macOS which originally shipped with the computer from the factory.

NOTE: Before you attempt to install macOS 11 Big Sur or macOS 12 Monterey.....the boot volume must already be using the APFS file system. IIRC, the macOS 10.15 Catalina installer was the last one to automatically convert the HFS+ boot volume into an APFS volume. It is possible to use Disk Utility to convert an HFS+ volume to APFS while booted from the macOS installer in Recovery Mode. It should not be data destructive as long as the process is not interrupted & completes successfully.

You cannot update past Sierra using Safari alone. Not using the directions in the Support article, anyway.

Once you are running Sierra, open the Support article on the old Mac itself, and use the link for Monterey to go to the App Store page for downloading the Monterey installer. Be sure to use Safari and to have Safari chosen as the default browser, since there is some sort of "secret handshake" between Safari and the App Store. A handshake which, in my experience, other browsers get wrong (resulting in misleading messages that the item you are looking for is not available).

constantinraot wrote:

yes I am logged in

Then you should be able to use the Links in that same article, a little further down, to get each version you need from the Mac App Store.

How to download and install macOS - Apple Support

If you simply try to get them from the App Store, they will not be found, because they are "put away" to avoid downloading "by accident".

You must use the links in the article, and the method Servant of Cats has described in detail above.

Have you logged in with Your Apple-ID?

That would be a requirement to get stuff from the Mac App store