If GSM Arena's page on the [OnePlus 12](https://www.gsmarena.com/oneplus_12-12725.php) is correct, it can *only* run ARM64 native code: the processor cores in its Snapdragon 8 Gen 3 SoC can't run in 32-bit mode. For more about this, see [here](https://android.stackexchange.com/questions/253596/is-android-becoming-a-64-bit-only-operating-system/).

If the app requires 32-bit native code, which seems to be the case from your question, then you are stuck: your 'phone can't run that code. Rooting would not help at all, your hardware can't do it. 

It isn't impossible, in principle, for someone to write an emulator to run 32-bit Android native code on 64-bit processors, but I don't know of it being done. Running complete apps on it would be complicated, because of the lack of 32-bit libraries in a 64-bit-only Android operating system, and the interface with ART. The "easy" way to do the job would be running a complete 32-bit ASOP operating system inside the emulator, but that probably involves the 32-bit "device" having a separate identity from the 64-bit host device, creating a lot of additional problems. Plenty of people must have thought of this, and I can see why nobody has seriously tried it. 

The easiest solution would be to acquire a 'phone that can run 32-bit native code. Those are still around, but they won't be forever.