There are a few different things that can happen when you raise taxes on the biggest companies.
One is that the companies may choose to pass on the cost of the tax increase to their customers in the form of higher prices. This could lead to inflationary pressures in the economy and could also make it difficult for smaller businesses to compete.
Another possibility is that the companies may choose to relocate to other countries with lower tax rates. This could lead to a loss of jobs and reduction in tax revenue for the country that imposed the tax increase.