If the Chinese do land on Formosa, the US will have to also land to dig them out.
Mostly because it's 500km inside the Chinese naval A2AD bubble, which makes it very difficult to reinforce or resupply once the shooting starts.
Invading Taiwan in 2027, because Mainland wants their "wayward province" back for the centennial of the PRC.
A US landing in Taiwan would not be opposed unless China had already won. I also question the need (and ability) of the U.S. to land or supply Taiwan unless the PLAN has already been largely destroyed. It seems to me the easiest way to dig out PLA forces in occupied areas of Taiwan are via starvation and bombardment, assuming a political solution for their removal cannot be arrived at. Certainly no one is landing marines or risking landing platforms unless the anti access threat is heavily eroded and air superiority firmly established over any landing beaches…in which case, shore bombardment is probably largely meaningless.