Android Question Bluetooth bitrate

The bluetooth radio hardware is responsible to manage the speed and adapt it if necessary.
You are talking about the 'wired' com speed that is a different thing (i.e. the speed beetwen your microcontroller and the BT module)

True. Silly on my behalf. I have used the type 'Serial' to interface to a BC127 Bluetooth module. The interface to the BC127 was an FPGA
that used the default 9600 baud rate for communication. I have a new application that needs faster comms. The BC127 has a programmable
buad rate that can go up to 921200. If I change the rate to 921200, can I assume that the Android app using the type 'Serial' will automatically
keep up with the new speed. Thanks

I think yes, it depends on the hardware of the phone and his drivers, imho.
The environment around the 2 devices and the distance has a big impact on the bt communication speed.

Thanks for that. Once the hardware is available I'll give it a try.