[mkodama]

To answer the question, holding the OFF button on a 2017+ car disables everything, including the “brake LSD” the previous cars needed the pedal dance to disengage. This only applies to manual cars and not automatics.

See bottom row of chart on page 254 in a North American 2017 manual. Picture attached.

EDIT: Subaru's Electronic Brakeforce Distribution EBD remains on; this electronically varies brake force between front axle and rear axle under hard, sudden braking.