Hi @BDC_Patrick
Like @FishBone0 said you can clamp inside the function:
UFUNCTION(BlueprintCallable, BlueprintPure=false, Category="Testing")
void DoThings(int A, int B, int C, FVector3d& ReturnPoint);
...
void AYourClase::DoThings(int A, int B, int C, FVector3d& ReturnPoint)
{
A = FMath::Clamp(A, 5.f, 50.f);
...
}