How to get the suitable block size when using littleFS

Hi, I am using littleFS to store the products data into ROM of MCU.
It set the block size for using LittleFS.
It works propely but I would like to know how to get the sutable block size for LittleFS. It’s okay to get the suitable size for my application condition. I mean it is fixed the data format to store the ROM using LittleFS.
Algorhizm of LittleFS is quite complex. It writes the data to the ramdam area where it has.

However I would like to adjust the size of ROM area of using LittleFS for reduce waste area.

How do I get the sutable size? Does anyone have idea?