If you are creator on OnlyFans then that means your running a business and you are not an employee of OnlyFans.
Since you are not an employee of OnlyFans then OnlyFans does not automatically takes out any taxes on income that you receive. So you have to pay the taxes yourself for that year.
There is not tax deduction on the income you received from OnlyFans.
OnlyFans does not pay any tax on behalf of you so at the end of each year you have to estimate your income and pay the tax on that amount.