cacheSizeBytes property
An approximate cache size threshold for the on-disk data.
If the cache grows beyond this size, Firestore will start removing data that hasn't been recently used. The size is not a guarantee that the cache will stay below that size, only that if the cache exceeds the given size, cleanup will be attempted.
The default value is 40 MB. The threshold must be set to at least 1 MB, and can be set to Settings.CACHE_SIZE_UNLIMITED to disable garbage collection.
Implementation
final int? cacheSizeBytes;