Weaker weaker ask, the Great Ocean Road navigation, whether only need to input the starting point, for example, from Geelong to Apollo Bay, navigation will guide inland? Do I need to set up anything ?

The Great Ocean Road has no forks. You can tell from the map whether it leads to the interior.

There will be different routes to choose from.

Yes, Google Maps will show two routes, one along the Great Ocean Road and one on the highway.

You definitely won't take the inland B100 to get to Apollo Bay.