Can a wife pronounce talaq herself?

In principle the power of talaq lies with the husband, but the husband may delegate that power to his wife (tafwid); the wife also has the routes of khulʿ, fasakh and taʿliq.
In tafwid, the husband says for example "divorce yourself if you wish"; if the wife promptly replies "I divorce myself", the talaq takes effect. The Prophet ﷺ once gave his wives a choice (the verse of takhyir), and they chose to stay.
In Malaysia, divorce must still go through the court. A wife who wishes to separate usually uses the route of khulʿ, fasakh or taʿliq. See talaq & divorce.