Typo in my text, can't correct it now. But you can simultaneously log into multiple Google accounts by putting each into a different container. These containers are mapped onto tabs. So in one tab, one Gmail account, in another tab, another Gmail account. And it's not just Gmail it's anything that you might want multiple accounts in (eg: AWS)

The containerise extension is the cherry on top. Once you've set up your containers, it can recognise URL patterns so you can set up bookmarks for each Gmail account and they'll automatically open in the correct container, already logged in.

If you have multiple awa accounts it's a godsend.