If you are unable to update the app, please follow the steps below.
Please note that, depending on the version of the Google Play Store, the language used may differ from what is described below. Please contact Google Play Store customer service for additional information.
① Open the Google Play Store, then tap the Google Account profile icon in the upper right of the screen.
② Tap Manage apps & device
・Tap See details under Updates available, then check to see if Fire Emblem Heroes displays next to an Update button in the Pending downloads list.
・If it does, you can update the app by tapping the Update button.
・If the Update button does not display or you cannot update the app, please see the Google Play support page.
https://support.google.com/googleplay/answer/7513003?hl=en&rd=2&visit_id=1-636500502891747665-3973811408
If the above does not resolve your issue, please contact Customer Support via the Inquiries form at the bottom of the page.