Asus no more than any other manufacturer will ever be able to do anything for you, it is the game publisher who defines the graphic parameters, and Moonton does not do it according to a SOC but device by device !!!! and to piss users off, there is no official list of devices that support 90/120 fps. (at least never found)
You have 2 solutions, request support for 90/120 fps here, in my opinion useless because if the ROG 3 is still in 60fps it will surprise me if the request succeeds.https://forum.mobilelegends.com/
With a lot of luck here is the answer you can have, which does not mean that it will be done
Every suggestion is submitted and read by our developers so it is for sure that they are working on optimizing the game to run on 90-120 Fps for all the devices that can run it.
It may take sometime but rest assured when possible it will be optimized and released.
Stay tuned and happy gaming.
You will have much better luck searching for yourself, Google is your friend, plus it's quite easy to do and without Root, especially avoid the solution of a modified game APK, memory on the old phone of my son, it was enough to make him believe that it was another phone and to put a file of the games of this other phone.
If you ever plan to buy a new phone later, ask before in the mobilegends forum if it supports 90/120 fps, it's not because it will have a dimensity 9000 or Gen 8+ gen 1/2 that it will enable these FPS.