i-cloud sign in

hi

I have 2 i-phone devices. Can i access/sign up i-cloud in the same PC?

Do i just sign in the one i-phone i want to access and then sign out when i want to access with the i-phone? i am worried that if i sign out on 1 i-phone, i will lose all my data in that phone ....

appreciate if someone can help advise. Thanks