How to lock a stolen iPhone 11?

my iphone 11 was stolen yesterday. My brother bought in Singapore. I still have box. I still have Imei number for this phone. Would you like to help me lock this phone? Because there are our family personal in this phone, my photos...

I have two iphone, 7plus and 11. I love iphone because ios safety. pls help me!

Thanks so much

Seri: C6***N73

Imei:

[Edited by Moderator]