Iphone how to access it if its locked?

My friend found a iphone he threw away the sim card but turns out the iphone is locked and he can't acces the settings like when he goes to check how much gb it has it won't let him access it it only lets him access the safria and another app. I was going to buy it from him and unlock the stuff but what if it won't let me access anything and i waste my money over the phone. So my question is if i unlock it at the store will i be able to access the Gb and the settings and will they make me unlock it?

Yes, unlock it and you will be able to access all the info. Locate the IMEI number and get the info about the phone via the IMEI number if you really need to know the model / GBs / etc.

Such an IMEI checker can be found either on eBay or any other unlocking site. Check below for more info.

For unlocking you would have to know the original carrier.