Get only one item & update only needed fields - Power Automate

 Instead of using Apply to each after Get Items & then updating the value. We can get only one item using expression.

outputs('Get_items_2')?['body/value']?[0]?['ID']

Then we can use Get Item action, to list the required fields.

Also if we need to update only one or a few columns we need to just update those columns rest we can leave empty.

If we want to update blank record we just specify null in the update.