How do interest rates affect indices?

Let’s consider, for example, the interest rate of the Central Bank. If it increases, then the country's currency will rise and key indices will probably fall. If the rate decreases, this leads to a decline in the currency. However, investors believe that this is in the hands of companies, since they have the ability to take out more advantageous loans and the shares of these companies will begin to grow, which positively affects the indices.