If you have filed the 2020 tax return the method of receiving the tax refund cannot be changed.
The IRS will not be accepting or rejecting any 2020 federal tax returns until late January.
If the IRS reject the tax return you can then change the method of receiving the tax refund and e-file again.
If the IRS accepts the tax return then when the IRS attempts to direct deposit the refund the bank will reject the deposit. The IRS will then mail you the refund check to the address on your tax return.