Attacks against unencrypted android phones?

So, I keep reading again and again that one should encrypt his android device.

But from an attacker’s perspective, what can be done with an unencrypted phone? Can I extract all the files or possibly install malware by accessing the file system on the phone, or can I unlock the phone?

I have bought a new phone and I want to test what can actually be done. So, what can be done?