I don't think China will invade Taiwan; at least not in a military sense. They're working on strengthening the image of the PRC in ROC but that doesn't appear to be working so well at the moment. Economically trade is very one sided at it happens- if Chinese seized all the ROC businesses and rounded up the businessmen it would have a pretty strong effect on ROC. Even if the US is tied up with Iran there are still a lot of resources the US can throw at the area.
I think a blockade would be more likely at this stage than a full blown invasion. They can force a surrender that way but it's still incredibly risky. I don't know what the PRC has planned but I doubt an invasion is too high up the list.
In my eyes that is the only realistic way China could possibly win.
A blockade, starve the Taiwanese population. Force their surrender without risking so much bloodshed. However I don't think the Taiwanese would surrender in just a matter of months.
If it really came down to a full blown military operation, then let's break it down. No outside involvment. So Taiwan is on it's own.
China has a big advantive in satellites.
IIRC China has a lot of ballistic missiles including SLCM/BMs. I suspect more than Taiwan would ever be able to intercept. Major targets would be aistrips, both military and possibly also civilian, bases and ASM and AA systems.
IIRC Taiwan uses it's vast mountain ranges for some of military instalations and probably has material and aircraft safely stored inside the mountains.
However disabling the strips and bases should more than suffice to severely limit if not completly ground all Taiwanese air assets, at least in terms of planes. Helicopters would still be a threat.
Even if China established total air supremacy and eliminated much of the primary defences, I think it would come at a great cost. Losses may be catastrophic for the Chinese airforce.
The Chinese Navy would face a dramaticaly inferior Taiwanese counterpart. Taiwan's options are rather very limited there. It can try to keep it's much smaller navy safe from major engagements or have it involved right away to defend the coastline and islands to the west, and contribute to protecting air space to some degree. So mainly shore based actions. I don't see it's capital vessels survive long in open waters facing so many enemy subs alone.
While taking out as many defences and aircraft as possible, the first obvious stage for a main land invasion should be to capture all the smaller islands and construct make shift assembly, supply bases and airstrips to use for operations from different angles. MIght be very useful for the deployment of army air assault brigades. It might also be totaly sufficient to focus only on the occupation of said islands, and then negotiate a ceasefire. Could be a much smarter move on the long run. China would establish proper bases surrounding Taiwan and prepare for following stages, in relative peace over the next months / years. That is if the Taiwanese accepted such terms. They might be pressured to do so by a blockade. However I think that unlikely.
China currently has a specialized landing force of about 12.000 Marines according to wiki. It can seemingly muster two divisions of paratroopers, however the PLAAF is supposedly only able to airlift some 11.000 men at a time. Said troops have to reach their destination first. Might come at a great cost. But let's assume the Chinese land all their assets unharmed. They would be dramaticaly outnumbered and outgunned in almost every scenario when attacking the main land, even if supported by army air assault brigades. Those forces would heavily rely on the support of Chinese navy and airfoce. Otherwise the Taiwanese will answer with greater numbers and local firepower. They will in all likelyhood have mobilized and recruited more people at that point.
Those numbers could naturaly also be complete bs so if anyone got better sources and input, please share.
I just don't think that China could simply assemble all it's vessels to carry tens of thousands of troops to Taiwan's beaches in one go and repeat. The logistics and loss of life would be insane imo.