The amount of taps is set in hardware. Systems that can do correction at >48 kHz for example utilize more taps to make that correction. In the case of StormAudio, they use two processors but restrict the correction to 48 kHz, resulting in twice the taps available.
That said, if you think about PEQ, there are a bunch of different ways to achieve the same curve (think about REW’s auto EQ). That optimization may be better with MultEQ-X as compared to the iOS app. My understanding is that the iOS app just sends a curve to the processor to do the calculation whereas MultEQ-X actually uses your laptop/desktop CPU to generate the filters when transmitting the data.
That would give better tracking of the target curve without needing more hardware.