1. Your data is safe
Without the master password from SafeInCloud, no person can get access to your data. Your data is always encrypted with a strong 256-bit Advanced Encryption Standard (AES): on your devices and in a cloud.
2. Lock phone
If you are worried about the data on your device, it’s possible to lock your device remotely if an appropriate function is enabled.
Android:
https://support.google.com/accounts/answer/6160491
Apple:
https://support.apple.com/guide/icloud/use-lost-mode-mmfc0f0165/icloud
Huawei:
https://consumer.huawei.com/en/support/content/en-us00887442
3. Protect cloud
To avoid the possibility to get access to your cloud, it is preferable to deny cloud access for the lost phone.
How to deny cloud access:
Google Drive (deleting device from trusted list):
https://support.google.com/accounts/answer/7177579
Dropbox (deleting data + sign out on a lost phone):
https://help.dropbox.com/accounts-billing/security/delete-dropbox-device
OneDrive (change password):
https://support.microsoft.com/account-billing/change-your-microsoft-account-password-fdde885b-86da-2965-69fd-4871309ef1f1
iCloud (change password):
https://support.apple.com/HT201355