I have not filed in a few years can I file all them together or does it have to be 1 at a time

The TurboTax online edition is Only for tax year 2023.  You have to file each tax year individually.

To complete and file a prior year (2022 thru 2020) tax return using TurboTax you would need to purchase, download and install on a personal computer one of the desktop editions for each tax year required from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/

A prior year tax return can only be printed and mailed, it cannot be e-filed using TurboTax.

Use a separate envelope for each tax year being mailed.

Yes, you can file your past due years now, but you have to file a separate return for each year and include only your income for that year. 

You can file your 2023 tax return using the current TurboTax online program, but for the earlier years, you need to get the software by disc or download. Follow this link to get prior years programs.