AutoNumbering Columns in SharePoint List

The above solution by DaveMehr365 is a direct response to the question, and is a good solution.

If you want to avoid a Power Automate component, you could try the alternative below.

1. Use the system ID column as ID

In every SharePoint list, there is a system column "ID" which contains a unique ID determined as an auto-increment. See screenshot below to show it. (Browse to the SharePoint list in question, then click on "All items" at top right, then "Edit current view", and then check the box next to the ID column.)

This follows a good practice that ID columns are probably best to not have significant prefixes or suffixes in them. If a row is deleted later, the related ID will be deleted and never be re-used. This is desired behavior.

2. Create your own Document ID column as text

You can create a separate column, call it "Document ID", and format it as Text. Presuming that you have the columns 'Year' ("2022") and 'Document Sequence Number' available ("205"), you can use a formula to concatenate them into a "YY-NNN" string, where YY is the last two digits of the year ("22"), and NNN is the sequence number of the document ("205"). Each document would then have a "Document ID" in the format that you look for. This would not be a primary key in the technical sense. 

In other words, the "Document ID" column is the business identifier that you can use in your work processes whenever end users interact with an ID.

The "ID" column is the real primary key from a system perspective in SharePoint. You would probably not reveal that to end-users.