You don't need to know the length or password complexity of a password. When setting the parameters to crack passwords you set a minimum/maximum and define the character sets. The parameters should be set to fall within a reasonable time frame which is dependent on the resources of the system you are using. I would usually set it to a month since most organizations force resets every 60 to 90 days.
This isn't something you would do for a single account, normally it's a password hash pulled from a db. All of the low hanging fruit passwords will be cracked really fast, like within seconds. There isn't any point in setting parameters for something that will take years so those user accounts will remain safe. Granted, this is only one type of attack. Normally password attacks are done with a sequence of various attacks. You can have a lengthy password that will still get cracked easily.
Butterfly1988!! is technically a lengthy and complex password but a dictionary attack will crack it fairly quickly.