Welcome to the forum.
You can get various lifts from Snake Racing, Calmini etc for different Navara models. From 50mm (2") up to 125mm (5") lifts - depends what model you have as to which way you go about it. The D40 has coils up front, so without changing the upper control arms you're limited to about 40mm of lift. The D22 has torsion bars and you can go a little higher than you could with the D40 without changing other bits.
In the end it comes down to how much you want to spend on it.