Car rentals difficult in 2021
The First Law of Economics
As noted in a separate thread, for an upcoming trip I found the car rental (for a week) to be about double what I would have expected, but cars were available. Oddly enough mid-sized cars were cheaper than compacts or even subcompacts. Again that's probably due to supply and demand issues. On the other hand, the plane tickets were surprisingly low-cost (not quite the same as cheap) so the two charges sort of canceled each other out. While the rental companies can sell off excess cars, it's much tougher to sell off excess planes.
The main thing to keep in mind, I think, is that you'll need to remain flexible with your travel plans until the economic impacts of the COVID pandemic sort themselves out and travel returns to 'normal', probably not until next Spring.
AZBuck