Received a Schedule K-1 Form 1065 and I'm trying to amend my 2020 tax return on turbotax online. Form 1065 isn't listed as an option. I've tried under "Wages & Income".

Use "K-1" as the search term. 

K-1s are entered in the Schedule K-1 interview of Business Investment and Estate/Trust Income.

See the attached screenshot for aid in navigation;

Hi ToddL99.  Thank you for the quick reply and screenshot.  I really appreciate it!  It turns out I need to upgrade to Premier to be able to amend with a Schedule K-1 Form 1065.  Thanks again for your help!

To enter the K-1 in TurboTax Online [Premier version or higher], please follow these steps:

1. Click on Federal > Wages & Income
2. Under S-corps, Partnerships, and Trusts, click on the box next to Schedule K-1. 
3. On the Tell Us About Your Schedules K-1 screen.  Click on the Start/Update box next to the type of entity (partnership, S-corporation, or trust/estate) that issued the K-1.     
4. If you have already entered K-1 information, you will see a Summary screen.  Click Add Another K-1 to enter your information  (or click on Edit to continue with the existing form entry).    
5. If you haven't started entering K-1 information, continue through the screens, entering the requested information.