At the campaign level, there are no limits on the amount of creative packs you can have. However, there is a limit of 700 per advertised app. Keep in mind your iOS app is considered separately from your Android app, so each one can have up to 700 creative packs.
However, for iOS, due to new limitations in the SKAdNetwork framework around the removal of country information, advertisers are required to limit their combinations of live campaigns and creative packs to 50 per app. This will help you obtain more accurate SKAdNetwork reporting by supporting the correct association of installs to campaigns and creative packs.