Joe isn't going to be able to "expand" the ACA if SCOTUS has thrown it out and it no longer exists.
This defines exactly what irks me about many on the more progressive left wing. They don't understand POLITICS and they don't understand LEGISLATING. They know issues, but are clueless on how those issues can be effectively implemented.
First, IF Biden wins and the Democrats take control of both the House and Senate then neither healthcare nor abortion will be impacted. In fact, both will be strengthened as matters of actual law.
Here's why. The ACA is before the SCOTUS because of a TX prosecutor who threw crap up against the wall and found sympathetic rightwing judges willing to ignore what Congress had actually done itself, elevating their view for Congress'. The case revolves around the mandate which the GOP invalidated as a matter of their amendment of the original law.
All the Democrats need to do is rewrite the ACA word for word and specifically recodify either a mandate or leave it out entirely, and have Biden sign the bill. My belief is that the Democrats will try to improve the many flaws in the ACA which the GOP would not allow them to in their decade-long quest to kill it. At that point, the case in front of the SCOTUS becomes moot, and any challenge to the new legislation would have to start from scratch because the two would be wholly different laws.
So now we're save ACA or whatever better will replace it. On to abortion. The only reason abortion is under threat from the SCOTUS is that up until now there has never been the political will to actually pass a law codifying the right to choose. The right wing's legal argument with Roe is that because the Court itself created the legal right to choose, it's unconstitutional on its face. So again, if Congress passes a Right to Choose law - with defined permissions and limitations to abortion - there is nothing that the SCOTUS can do about it if and until cases opposing the new law again start from scratch and work their way up through the system.
Both of these reasons are why electing Democrats all across America is imperative if you don't want to see both issues outlawed. And in the same vein, Democrats will entertain more progressive policies if the public's mood and the fiscal analysis shows that they are the better way to go regardless of the stances politically taken during the election cycle as long as it best benefits society as a whole and they have enough votes to pass the legislation.
If the Democrats don't have the power, there is absolutely ZERO CHANCE that the GOP will ever pass such legislation unless it absolutely becomes a matter of life and death - and even then they'd be hard-pressed to marshal a majority. Many in the GOP would rather practice nihilism than admit that the libs are correct about most anything.