Check out this tweet to see a gif – it’s quite neat. You can swipe down on your avatar on the top right to switch accounts. Works only on iOS though. Can’t wait to see this on the Android app.
If you want to time travel and see things you may have written even ten years ago, go to ‘All mail’ in Gmail and hit ‘Oldest’ on top. You’re going to have a nostalgic trip with some great memories, I promise.