Sorry @Jason_Castelino missed this. Right, the STT of 0.1% is applicable if you have 2 open positions on expiry that result in a net-off (Long futures and short call options, short put, and short future, etc) you are not required to give or take delivery for the position. However, there will be STT charged on the long position(s) as this is treated as notional delivery.
If you let the long ITM option position expire, then STT of 0.125% is applicable on intrinsic value of the option. Not on the contract value. You can check out this post for more information:
If you’re an option seller then this 0.125% STT is not applicable as it is already paid when option is sold. Which is 0.05% on sell side (on premium).