How to reduce the size of "CloudKit"

Hey jinsheng6226,

We understand you're wanting to reduce the amount of CloudKit storage. For information about freeing up storage on your Mac, click here: How to free up storage space on your Mac

CloudKit includes data from iCloud Drive, Photo Storage, etc.

Take care.

See used and available storage space on your Mac - Note -

• Other: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

Since the Internal Drive is the very small 128 GB Size Drive - one should purchase as reliable External Drive SSD and move as much of your photos, music, videos, podcasts, and iPhone Backups Off the internal drive to the external drive. That and inventory Application that are not used or needed and remove them as per Developers Instructions. Further, empty the Trash.