I bought the Samsung Galaxy a51 and installed Fortnite on it. It has all the system requirements, but it still jerks.
System requirements:
4GB Ram
64 bit
Android 8 or higher (have Android 10)
Can't be fixed. The cell phone has too little power
The a51 only has a maliG-72 and a not-too-fast Exynos
It has too little power
Your cheapest (A series is the cheap series, with bad processors and GPUs) doesn't do better.
But this applies more to the cheaper models
The expensive ones like the a71 and the a91 have partly built in Flasgship SOCs
Doesn't change the fact that both the processor and the graphics chip do not provide sufficient power.