I’m so new to Linux that I’m not sure what LUKS means, but I can confirm that when I first received my phone, that prompt to enter the password for disk encryption was already there. I had to quickly read through the 4 page doc that was included to see what the default password was.
For your 2nd question, yes, the password screen was previously coming up.
I’m not exactly sure how to do this Jumpdrive - would you elaborate?