You can only call a discard to complete a set of 3 or more identical tiles (not for pairs or single tiles), unless it's the last tile you need for Mah Jongg. Since "2023" is a set of 4 single tiles, you could only call a discard for that grouping if you're one tile away from Mah Jongg.
For more information on this rule (and many others), please feel free to check out this tutorial.