In the Display & Video 360 API, advertisers can now add or remove channels, digital content labels, and sensitive categories at advertiser level. Google says the targeting changes are then applied to all current and future campaigns.
On the API update, google introduced targetable entity management that allows advertisers to create and update Inventory Source Groups, Negative Keyword Lists, and Location Lists. Channels can now be updated as well, but not created.
According to Google, a new Creative entity field lineItemIds (output only) now lists the line items the creative is currently associated with.