Hello. My main question is covered in the title of this post.

I have experience with installing LineageOS, and currently have it on a Fairphone 2. However, this question is pertaining to a friend who has a Google Pixel 3 that is not working properly. It frequently shuts shuts off and reboots after being turned on. She often needs to hold the power button to be able to read texts without it going blank and rebooting. I suggested she may need to free up some space, so she deleted some video files from it, and there is sufficient space now, but this made no difference.

So, as outlined in the title, I’m wondering if a LineageOS can be installed while preserving her user files – similar to installing a different Linux distribution on a computer that has a separate /home partition (IE, preserving the home partition). Is this possible on an Android phone such as the Pixel 3?