It depends on the type of company. Usually, it is not necessary for small and medium-sized companies, especially for products and not services.
If you market well for your products, people will start buying as soon as you start your business if the pricing and advertisement are available, which will help you cover at least 50% of the operating price. Thus, you won’t need it in the first 3 months, but my advice for you is that the amount can be obtained when any problem occurs, such as taking a loan from the bank or getting them from a relative but returning them quickly.
However, if the company continues to operate well but lacks a small amount of money for rent or salaries, and if you cannot provide this amount, the company will not succeed. So, you need to have a larger amount. If the feasibility study is correct and has the estimated amount of capital, then you will only need the capital.