I did a quick search on this forum for an iPad arranger and found posts on Midiband. The posts are two years ago. Now they have version 3.1. I donwnloaded the pro version. 50 % sale mere$1.99. There are two different free versions to try out. It played well Yamaha .sty files. I connected my Korg Microkey 61 and sent the midi out to Sound Canvas within my iPad. It sounded pretty good.

I have Live Styler in my notebook but iPad is so much more portable and the setup is much easier.

https://forum.audiob.us/discussion/8921/midiband-3-0-is-out-pro-music-arranger-app-for-ios/p5