Designing from low-voltage 3-phase motor driver for more powerfull BLDC motor
You might consider switching to a motor driver that uses external FETs instead of integrated FETS. For example the STSPIN32F0, which even has a microcontroller in the same chip.

You could add higher-voltage FETs to the output of your driver, but then you'd have to deal with timing to make sure you don't turn on two FETs that short your battery... I highly recommend you use a chip more suitable for your task rather than adapting the one you have.