Need some advice

So I have my main on my phone and my second account on my old phone. I'll be travelling for 3 weeks and can't take the old phone with me as well. Both accounts are linked to Google accounts. Can someone confirm if I should be able to log in with both from one phone and how I can go about doing that?

Old posts I found mention transfer IDs but since the security updates a while back I'm not too sure that would be viable.

If someone has any advice on this I would love for you to share.

Much appreciated