You can earn interest by putting money in a savings account, but savings accounts generally earn a lower return than investments.
You can earn interest on fiat cash, but not on Bitcoin. The value of fiat cash decreases with time, due to inflation. That is why the banks pay you interest to deposit fiat. On the other hand, since it is protected against inflation, no interest payments are required for Bitcoin deposits. If Bitcoin replaces fiat cash, the practice of giving interest for deposits will come to an end.