How did you determine that those files are fragmented?
The way an SSD presents data to a file system has little bearing to how the actual data is stored in the cells of the memory chips.
Wear leveling, garbage collection and TRIM mean that on any modern SSD and OS, the bits that make up a file will move from block to block, cell to cell, over time. Whether all the bits are together or scattered around the drive, makes no functional difference to performance.
Fragmentation, in the sense of files on a file system, means the data comprising a file isn't contiguous and sequential. On a HDD this actually means something, but on an SSD it just doesn't. For the end user an SSD is a black box where data goes in, and data comes out. Where it lives within the device, is more or less indeterminable.
If you're worried about performance; don't. If you're worried about SSD wear; don't go 'defragment' because it doesn't make data contiguous within the actual chips. You'll just wear the drive out faster and accomplish the exact opposite of what you were intending.
TLDR: You might defragment files within the file system, but the file system itself isn't contiguous on an SSD. Data shifts around underneath to make the SSD last longer.