If you plan to visit as many museums as possible during your visit to Paris, consider buying Paris Museum Pass.
Paris Museum Pass includes admission to 60 museums in Paris and Paris region, and is valid for 2, 4 or 6 consecutive days. You can also skip-the-line with most museums included with Paris Museum Pass.
While it is not physically possible to visit all 60 museums in just 2 days, you can still enjoy savings vs buying regular admission tickets, and benefit from skip-the-line entry to most museums. If you plan to visit 4 museums or more during your 2-day exploration of Paris, purchasing Paris Museum Pass makes sense. If it is just 2 or 3 museums, it is best to buy separate tickets for each museum.