Can I access to different iCloud accounts on my iPhone?

I want to know if i can log in from different iCloud accounts on my iPhone without any trouble or if i will only be able to change my icloud account once? Im going to log in my icloud account on my brothers iphone to see if i can access to my whatsapp chats from there. and also wanna check if i can access to my whatsapp chats without having my chip inserted since my iphone was stolen.. i also tried to download programs that can download and extract your icloud backups but so far no one has worked... thanks