You can use the Photo Editor one. Search on the Stickers option, you can find there at the Calendar sticker pack. If your problem is solved, please accept my comment as solution to help others by clicking at 3 dots on my comment!
Officially there is no watermark tab..but you can add it manually
Open gallery>select any image>click on edit pen>select stamp section>and then click on calendar like icon>here select device and date stamp
Open gallery>select any image>click on edit pen>select stamp section>and then click on calendar like icon>here select device and date stamp
