I think I misunderstood this originally, I was thinking that harmony had a module for the sensor you were dropping into your project graph.
Assuming this is not the case, you are going to have to write your own application/driver for the sensor. Like vghandi mentions, it probably makes the most sense to start with that example for the I2C EEPROM and modify it for the sensor.
The first thing you are going to need to do is determine what the I2C ADDRESS
is, this is the address of the chip itself. It has nothing to do with the register locations in the chip. You would want to modify the read and write function calls to include this address.
SERCOM7_I2C_Write(APP_AT24MAC_DEVICE_ADDR, &testTxData, APP_TRANSMIT_DATA_LENGTH);
So you would need to replace APP_AT24MAC_DEVICE_ADDR with the 7-bit
address for your chip. I took a peek at the datasheet and it says the Slave ADdress (SAD) is 110101xb (either 0x6A or 0x6B). It looks like there is this SAD bit that is based on if the SDO/SA0 pin is connected to ground or VCC. Look at page 35 of the datasheet and see if you agree (or maybe someone else on this forum can).
#define APP_LSM6DS3_DEVICE_ADDR 0x6A (or 0x6B)
SERCOM7_I2C_Write(APP_LSM6DS3_DEVICE_ADDR, &testTxData, APP_TRANSMIT_DATA_LENGTH);