This is a short take. EURNZD has shown an initial sharp switch for the south on 4H time frame. Looking at the history of this time frame (over the period shown), this usually is followed by further travel. How far? I don't know. See chart snapshot below.
But this pair is a very volatile one so don't expect it to go down smoothly - and there may be nasty surprises. Whoever said trading was easy?!
Note that this is primarily a trend-following strategy. So, this is not about pre-defining targets. There are no targets in true trend-following. Stop-losses are larger and potential gains are much larger than 80% of what is not trend-following.