Heads up: it's looking grim.
I found [https://www.gsmarena.com/blu_vivo_xl2-reviews-8544.php|this thread] and this other question ([post|416765]) with people having the same issue. So far, I have not seen a solution. However, you might want to explore [https://forum.xda-developers.com/vivo-xl/development/rom-aospextended-rom-v4-1-t3592932|this website.] It appears to be unofficial developers seeking to fix things, but I'd advise reading their fine print for yourself. Since I had to look it up myself, here's an [http://www.androidauthority.com/what-is-a-custom-rom-android-74072/|explanation of ROM.]
Good luck!