Is it possible to update default ID column of a SharePoint online list with our own value?
No, this is not possible.
SharePoint list item ID is read only property, you can't update it with custom value.
Reference: ListItem.Id property
If you have a Custom List, you have to add (display) ID Column manually. Here is how you do it:
- If you are using a modern list, click +Add column > Show/hide columns
- Click the checkbox next to the ID field, then hit Apply. You can also drag the column to the top if you want it to appear on the left side of the list
- Don’t forget to Save the view so that changes won’t be lost
- The column will now appear in the list
- If you use a classic list, you will need to edit the view.
- You can rename the ID field to a friendly name if you wish (i.e., Risk # or P.O. Number)
Hope this was helpful for you.
It's not possible to update the default ID column of a list in SharePoint online. ID field is an auto-increase column and it's read-only.
You could always recreate the list and add the items again in the proper order, or create a custom 'id' column to replace it.
And if you want to change the column name, you may have a look below method: