Beijing doesn't lose anything from feinting landings from day 1. If Taipei wants to defend that area, they'll need to move and setup troops in static defense positions, these troops are like fish in a barrel for the PLA to shoot at when they have 10cm error margin satellite targeting and tons of AEW drones flying around the area uncontested.
China doesn't have to land in the first day, but it can make feints and if Taiwan fails to detect one, those troops will land. If the rebel army instead manage to setup defenses, they'll be a bombing target and PLA can feint at another area. The rebel army is 150-200k strong, if PLA artillery mow down tens of thousands in a few days time (and even the far older PLA of 1979 showed such capability to inflict terrible casualties against way better trained Vietnam army), there won't be anyone left to staff the defenses.
The more overwhelmingly China moves against the rebels, the more US and Japan will be deterred from invading. To use Ukraine as an example, imagine if Kiev had attacked the rebels in 2021 with 30 000+ precisely targeted shells a day while Ukrainian formations rapidly flood into the Donbass as the LDPR loses almost all their equipment to strikes and suffer complete blackout & blockade. Would Russia still have conducted a special military operation in 2022 then? They would be cowed because 1. Ukraine showed its overwhelming capabilities 2. There is no organized army left to reinforce in the separatist territory.
Once China has confirmed the unwillingness of the rebels to go on the negotiating table or threat from US steps up too much, China shouldn't sit and wait for America to declare a SMO. Instead, they'll hit the rebels first. I think that is what Chinese planners are doing now, and they obviously have far greater insight into the exact "red lines", but most likely it is related to monitoring upcoming leadership changes in Taipei.
