Didn’t you check the whatsapp latest sticker update? You might need to install it from whatsapp official website since they are not rolled the latest update to all the android devices via playsotre yet.

Link https://www.whatsapp.com/android/

Check this Sinhala reply sticker pack from SAUSECODE LABS.

https://play.google.com/store/apps/details?id=com.sausecode.whatsappstickersinhalareply