You may not need a ramp at all, and typically a small platform to jump on mid-way is a lot more space-effective and rabbit-friendly. Ramps tend to be too steep and/or not covered in a texture/material that is pleasant for rabbit feet.  Ramps that are gradual enough (i.e. not steep) tend to take up a lot of space because they are so long.

If you’re comfortable, you can share a picture of where you want the ramp to be and we can share thoughts on whether to stick with a ramp or if there is something a rabbit and the space may be more agreeable to!

I think 26 inches would be too high, because it would have to be very steep, unless the ramp is VERY long.

Coincidentally my C&C cage is almost the same dimensions and I have a ramp going up just 1 level (so 14 inches in my case). The ramp does take up a lot of space (it’s essentially 3 grids long), but they seem to like using it. I think it could prob be a bit shorter (2 grids long maybe), but not by much or it would be too steep.

But I agree that you don’t need a ramp unless you want one! For platform heights, I usually go 1 grid high for each level up (so 13 inches in your case). They will be able to easily jump up and down at that height. Bunnies CAN just 26 inches, but they might not want to as much, and as they get older jumping down from that height often can be hard on their joints. A good rule of thumb is to make the levels low enough so that when the bun stands up on their back legs, they can see where they are going to jump to. And similarly, you want to set things up so that a bun cannot jump down a distance farther than they jumped up, to make sure they don’t fall and hurt themselves.