These two verses immediately follow the scene with Jesus upbraiding the Pharisee scribes, they are shown in quotes in my translation, as though this was a continuation of thought begun in verse 20. It’s not completely crazy – v20 is clearly metaphorical, as are verses 21 & 22. But these are wildly different metaphors, so there’s room to suspect that these two verses were later interjections into the existing text.
Both verses are in a specific formulation: “No one… (performs an incorrect action) otherwise (a bad consequence occurs).” The second verse adds a correct action to put a fine point on it. These may seem unrelated, but they are, in fact, referencing the same thing and both are speaking to the situation with Jesus breaking bread with upper crust Romans. Both are explaining why Rome had given up on civilizing the Jews and was going to create a new state with new peoples there.
In v21, the garment being indicated is the Empire, and the bit of new cloth came of the exceptions made for the Jews by Augustus, when they were allowed to retain a small bit of sovereignty regarding their temple. Clearly, this accommodation resulted in a larger tear than had originally been created by the persistent state of rebellion in Judea.
(continued on next verse)