I’m using these:
BIGTREETECH TMC5160T/TMC5160T Plus Stepper Motor Driver SPI Mode – Biqu Equipment
They come with a cable to plug them in to the driver sockets of the main controller board, with these I can run the Nema 23s at 48V whilst the main board and other steppers are still at 24V.
I just have 1 big fan covering the whole board without individual fans on each driver.