For 2001-2007 Toyota Sequoias:
The number one coil is located on the front passenger side of the engine, near the top. It is typically the closest coil to the front of the vehicle.
For 2008-2021 Toyota Sequoias:
The number one coil is located on the rear passenger side of the engine, near the top. It is typically the closest coil to the rear of the vehicle.