You can import ICS files with a single event or multiple events (entire calendar) with aCalendar.

When selecting an ICS file in another app (email, cloud drive, etc), aCalendar should be offered to open the file.

Otherwise, you can go to the calendar list (menu - manage calendars) and press the plus button in the bottom right corner to import an ICS file.

Single events open directly into the event editor, multiple events open a bulk-import view, where you can manually choose which events to import, which calendar to import into (it's usually a good idea to create a new calendar when importing many events), and set defaults with regard to colors and notifications.

See also ICS Export