Connect locked iPhone to Wifi

Hi, are there any way to connect iPhone to Wifi (to which it was already connected, so it has registered the password) when iPhone is locked?

I'm going to explain better.

I forgot the passcode to unlock my iPhone. I turned the phone off, and when I turned it on again, it doesn't connect to Wifi (I have no access to control center, and Siri as well, since it asks for the password).

Note:

• the wifi was previously associated with my iPhone (I mean: iPhone has the password, so it could connect)
• Before restarting my phone I've previously disconnect wifi connection (because I wanted to use mobile data instead of it) but NOT turned off the wifi (I just clicked the blue button on control center which so became grey).
• I need to let iPhone backup automatically with iCloud so that I won't lose my data before erasing it (but it will only backup if connected to wifi, that's why I'm asking this question).

Hope someone can find a solution.

Mattia