Your Linkt Tag, Tagless or Commercial account covers you for travel on all toll roads in Australia, including the Sydney Linkt network.
Sydney tolls are deducted from your account as you travel. If you travel without a tag, but the vehicle you're driving is linked to your account, you'll be charged a video matching fee, as well as the toll.
Alternatively, you can buy a pass for your Sydney travel.
To calculate your Sydney toll travel costs, try the Linkt Sydney toll calculator.