Huawei Honor 6X Emui 5.0 Android 7.0. Not Core GMS package problem
Did you try to install Google Play store apk from apkmirror?
Before install it you have to install


Google service framework 7.1.2,
google account manager 7.1.2,
Google Contacts Sync 7.1.2,
google play services 11.7.45 (430-174122868).


Find them on APKMirror, choose version that i recommended above for arm android 7.0.

Google Play store needs 4 apps above to work normally.