How do I target API 28 in version 2018.217f1 for my android app.(URGENT!!!)

I'v been working on this game in v2018.217f1 for 4 months now and it is reasonably close to release. However when I posted a Beta release on Google Play there was a warning message stating that after the 1st of April, apps with a target API lower then 28 would no longer be accepted, mine is target API 27 and that is the maximum I could set it to within the build player settings.

First I used Android Studio to install API 28 but that didn't seem to change anything. (My SDK preference is set to the same one)

Then I backed up my project and ran it in v2019 and I had the ability to target API 28 though there was bunch of errors that I managed to get rid of by deleting the package TextMeshPro however something that I couldn't fix was that the component NetworkTransformChild no longer existed which was pretty essential for my game. (I even updated the multiplayer package).

Considering today is the 22nd of June if I cant find a way to target API 28 and have my game still work properly I will have to release it within the next 9 days which I don't really want to do cause it will be rushed and unfinished. Please Help.