If a player is a 2nd-level sorcerer, and sacrifices one of their 1st-level spell slots to get an additional sorcery point, could they use their 3 sorcery points to create another 2nd-level spell slot?
The rules state:
You can never have more sorcery points than shown on the table for your level. You regain all spent sorcery points when you finish a long rest.
At level 2, your maximum number of sorcery points is 2 (the value is always equal to your level from level 2 onwards). It takes 3 sorcery points to make a level 2 spell slot, so it is impossible.