If you mean perspective distortion, the effect you'll get with a wider lens is larger separation between foreground and background. The closest parts of the flower will seem closer, and the farthest parts will seem farther. Using a telephoto lens, in contrast, compresses the foreground and background. I.e. the farthest part of the flower seems very close to the closest part.
Perspective effects like this will not affect a viewer's perception of 3-dimensionality.
3-dimensionality in a photography is produced entirely through the shadows produced by the light sources lighting the object being photographed.
If you light a face or a flower with the flash on the the camera, it will produce a flat look, because from the cameras point of view the shadows and shading are minimized. If you light a flower or face from the side, the shadows are plain to see and the viewer's brain locks onto those shadows and creates a 3-dimensional image out of a 2-dimensional one. That's why in
this photo I lit the flowers
with lights from the sides (I shot from the right side of the table for the shot I linked), hitting the flower in a kind of cross-fire.
I note in the notes for that photo that one flash failed to fire there. Even if it had fired, the cross-fire wouldn't be even. You want a dominant light source, and a fill (so the shadows aren't black). In retrospect, I'm pretty sure the 2nd flash
did fire, just not at the proper power setting because I didn't let it charge enough. There is still some fill in that image, just not as much as there should have been.
It's also possible that the 2nd flash didn't fire, but enough light bounced off the white umbrella to provide the level of fill you see in the photograph. Either way, it ended up being a happy accident.
So, to make a 2-dimensional image look 3d, you need to make sure the incident light creates shadows and tone variation that is visible from the camera.
A flash on-camera or sunlight behind you will not do that, but if you put the sun to the side of the subject, you'll get a more 3d look. Of course, you can't move the sun if the angle doesn't allow the composition you want...
that's why flashes are useful for macro photography!