I believe that if the IDF is to go on the offensive, Israel will advance in several simultaneous columns, with one covering the Lebanese coastline and the other covering the Syrian border and the Golan Heights, the goal being to close off some of the
routes for reinforcements and weapons to Hezbollah.
If Hezbollah entrenches itself in Tyre, we could see a repeat of what happened in the Gaza Strip, if the IDF advance is not stopped by Hezbollah. In the meantime, the IAF will push even harder in Lebanon, especially in the north, attacking command and logistics centers in Hezbollah's rear.
Clearly, such an operation will not be quick, and the fortifications prevent a rapid advance by the IDF towards the Litani River, without even mentioning the retaliatory strikes by Hezbollah that will clearly harm the IDF ground forces that will be within range of Hezbollah's weapons. Israel will need to coordinate its air defense and the IAF to allow the simultaneous advance of ground units.
This is the missing wild card in this game. If Iran joins, things for Israel will get even worse.
edit:
Israeli aviation has just bombed the most northerly target it has had since October 7 last year in Lebanon - hitting a target well north of Beirut, at a distance of 120 km. Thus, all areas of Lebanon are now target zones.