I need to file my 2018 taxes

TurboTax does not support tax year 2018.

You will need to use a local tax professional to assist you with the 2018 tax return.

Note - Any tax refund on the 2018 tax return will not be paid since it is beyond the 3 year limit from the due date of the 2018 tax return.

No, you can't file a 2018 tax return using TurboTax at this point. 

You can still file a tax return for 2018, if you didn't file, but it is a closed year. A closed year is a year that is no longer subject to audit, assuming the original return was filed on time and there is no criminal activity. 

At any given time, there is a current year (2023) and three open years (2020, 2021 and 2022). Earlier years are closed years.

You can't file a closed year and get a refund. 

You can contact a tax professional in your community to get help filing a 2018 tax return.