Follow these steps to back up your data if you have a 1SE subscription.
Make sure 1SE will be included in your iCloud backup by following these steps:
Ensure your phone is fully charged and connected to Wi-Fi.
Go to Settings > [your name] > iCloud.
Tap iCloud Backup and select "This iPhone" from the ALL DEVICE BACKUPS list.
Scroll through the apps list and ensure 1SE is enabled.
Return to the previous screen and tap Back Up Now.
Stay connected to your Wi-Fi network until the process completes. It may take a while. You now have a backup with 1SE to restore from iCloud.
If you'd like a more detailed step-by-step on how to back up with iCloud, check out Apple's help article.
Remember, logging into iCloud on your new iPhone doesn't equate to an iCloud backup. 1SE isn't saved to an iCloud account; only basic data like notes, mail, and contacts are. You must back up via iCloud backup or a computer.