I should have clarified, the pack I'm using has no primitives

https://kenney.nl/assets/shape-characters

I saw a post saying I can put it on a billboard (plane in unreal) so can I put it on a cube, or shall I use 6 planes to make a cube?

I'm doing the 2D 3D mix and 1 pack challenge

for your reference @kenney you can see my engine uses planes for the sprites, and if I put planes at different angles I get a cube

is this acceptable?

Ah thanks just got this, yeah I'm not importing anything. The only art is the one pack, it surely is a challenge and I'm looking forward to creating a video showcasing how I did it