After the phone is offline, can I still receive the short messages sent offline when I go online again?

First of all, it depends on the information validity period you set yourself.

This setting is in the information settings. There is an information center number and the information validity period.

If the validity period you set is one hour, the message you sent during the offline period of your mobile phone will be valid for one hour before you cancel the offline mode. If you don't cancel the offline mode after one hour, the message will be invalid and the other party will receive it.