You don’t get to choose, even if your parents have cut you off financially. You have to consider the situation for 2020 in this case. If, considering your age, residency for 2020, and financial support for 2020, you could be claimed as a dependent, you must check the box that says yes, I can be claimed as a dependent, even if you don’t want to be claimed.
If you answer no, that you can’t be claimed as a dependent, and your parents do claim you as a dependent, the IRS will send letters to both you and your parents to start an investigation. They will look at the facts as outlined in publication 501. Whoever loses the dependent claim will have to re-pay any tax benefits received along with interest and possibly a late payment penalty.
https://www.irs.gov/pub/irs-pdf/p501.pdf
