Not with Turbo Tax.  You can only buy the Desktop program for prior years.  You might have to go to a local tax place or accountant.

No.   Only 2020 can be filed online with self prepared tax software.

Paid professional using professional software can file past return online.

TurboTax no longer sells or supports 2016 since you cannot get a 2016 refund any longer.

Search some other tax preparation web sites. You might find one that provides online filing for past years.

Note that it's too late to get a refund for 2016 and 2017. You can file the tax returns, but if they show a refund you won't get the refund. If they show a payment due, you still have to pay it.

while some sites do offer online preparation of 2016-2019 returns, e-filing with do-it-yourself software for other than 2020 is not available. if you are due a refund for 2016 you have forfeited it by not timely filing the return. Turbotax no longer offers the app to prepare your 2016 return but does have the desktop apps for 2017-  2019

https://turbotax.intuit.com/personal-taxes/past-years-products

while 2017 is offered, unless you filed a timely extension, any refund is forfeit. if you owe, there is no time limit for the IRS to come after you.