If you are talking about a rigid, non-suspended mountain bike fork that could work except for the hub spacing is usually 100 mm on the mtb front and you need a 135mm rear hub for your gearing typically for a rear hub at the front. The easiest solution
@Don1 gives is some fatbike forks come in this spacing. Otherwise you will need some kind of modification as with the cruzbike kits mentioned by
@psb123.
However, a suspension fork is a big challenge.
Read on at risk of word overdose: if using a suspension fork that can move up and down then you will need the rest of the front triangle to accommodate the movement. Either flex, pivots, or both as in earlier Cruzbike kits and Silvio 1 and 2 models. Pivots, for example, would be needed in at least three locations if the rest is stiff: at boom to bottom bracket, boom to steer tube and chain stay to fork in order to let the fork move up and down.
All this equals extra complexity, weight, and decreased stiffness and results in higher cost, poorer climbing, and worse power transfer.
Front suspension is pretty attractive and would be awesome on rough roads but, unless you find a new way, is not a good fit for moving bottom bracket recumbents such as Cruzbikes.
The best solution currently used by Cruzbike, and they are the experts in the field here, is larger tires 1.5” = 38mm gives a pretty good ride on mine.