The SuggestDepth property in the GlobalConfig contains the value from 0 to 100 that controls how deep is the search for suggestions, greater the value longer the search and better the suggestions.

Remember to recycle the application pool after reloading the modified GlobalConfig.

<SpellConfig 

 ...

 SuggestDepth="10" 

    ...

IMPORTANT: To make these changes available to the GN4 users, after you saved the GLOBALCONFIG.XML file and imported it into the database, or after you modified it in EdAdmin4 and saved, recycle the GN4 application pools on all IIS servers and then make all users log out and log back in.