High-cardinality dimensions can cause data to aggregate under an "(other)" row. If you have a Google Analytics 360 property and you view a report with data aggregating under an "(other)" row multiple times, Analytics will enable automatic custom tables so your data aggregates under the "(other)" row far less frequently.
You don't need to take an action to enable automatic custom tables. They're enabled automatically for all reports, providing Analytics 360 users who use high-cardinality dimensions with a fuller picture of their data.
Analytics 360 disables the feature when no one in the property views the report in the past 60 days, at which point the data will resume aggregating under an "(other)" row. However, when you view the report again, Analytics 360 will re-enable the automatic custom table. Keep this in mind if you notice data moving in and out of the "(other)" row.
Automatic custom tables don't support some dimensions. If a report includes one of the following dimensions, then Analytics 360 won't use an automatic custom table and you will still see the "(other)" row: