Most of the kernel modules are loaded automatically at boot time. You can specify additional modules to be loaded by creating the file /etc/modules-load.d/<filename>.conf and eventually the file /etc/modprobe.d/<filename>.conf if you need to pass module settings to udev.
Example:
Create the file /etc/modules-load.d/fbtft-adafruit22.conf
fbtft_device
and the file /etc/modprobe.d/fbtft-adafruit22.conf to pass module settings to udev
options fbtft_device name=adafruit22