I’m not rich enough to know but is it an official, written, securing or isn’t just the bank ok to emit the loan since they just trust you because they know you

I’m not rich enough to know but is it an official, written, securing or isn’t just the bank ok to emit the loan since they just trust you because they know you are rich ? Especially if the loan is just a fraction of your wealth and you have a good history, the bank would probably agree to grant you the loan without real guarantee.