Hi, i'm not an expert on perspective but i think this image looks cropped due to a decision with your vanishing points. The Horizon Line is above half of the image, so i was expecting to find the lines converging in some point below the sight of the viewer. However, here you decided to make the lines of your box converge on top, so it looks like the box is a bit wider at the bottom, rather than looking like a perspective distortion. i think adjusting that would help you with this drawing.

Everything with the lines work looks correct using the vanishing points you have currently, but it the perspective feels a bit forced. I think the horizon is too high to have a top perspective look natural , which makes the top vanishing point look really forced. So I would move the angle of the camera so the vanishing points are all "off screen" and drop the horizon line to below the center of the image. Attached is guess at what that might look like. It would also give you a better chance to see what is in the cage in more detail and remove some of the background details that are less important to the storytelling.

Good overall I think. Just one note that you probably need to take care of (depending on what you want to express): You can't only care about vanishing points, you also need to be conscious about your optical centre. If this framing is not shifted (That is you essentially cropped the content off-centre instead of rotating the camera so that you get your stuff onto the optical centre), all corners in the frame should have equal "stretch". This is more prominent when you have a wide angle linear lens, the edge of the frame tend to stretch very heavily. Looking at your example image, it appears to be you wanna have a 3 point perspective with a vanishing point on top, that means your camera is actually tilted up and you have to only showing the bottom portion of that "tilted" view. (See attached image for a quick 3d demo) Some times this off-centre effect is used to deliver wide lens edge effect, establishing shots and so on, ideally also towards the edge of a page, normally not for main stuff because it stretches unevenly. That is not to say it's a bad drawing, just a loop hole that you might need to be aware of. That's why a lot of artist use curvy-linear perspective, much like a fish-eye, so the stuff towards the edge naturally wraps around, reduced this unnatural stretching effect.

It looks like you understand the basic concept and steps to plot out your vanishing points to make a three point perspective box so you are off to a good start. I think if your goal for a drawing is to get better at perspective, you may want to hold off on the organic objects and creatures for now and really push yourself to explore how you can use three point perspective to make more interesting complex objects. By putting this limitation on yourself you can try to experiment with what else you can create using only three point perspective besides boxes. You could try taking a box and work on adding pieces to it and subtracting chunks from it for example. You can try taking boxes and cutting them into letters or numbers or nonsense. Have fun with it and experiment. A major step forward for you might be to try arranging multiple objects in a space that don't share the same vanishing points (VP). For example, as the terrarium is now, it is placed perfectly parallel to the walls of the room, which in real life is unlikely to be the case. If you rotate the box a little bit it will feel more natural. Also different line weights can help define how far back an object is in space. If you use heavier line weight on the objects in front and lighter weight as they recede into space it will help show depth and what objects are in front of others. Go have fun with it and experiment.

Hi Kai, I would move the horizon line to the bottom of the page if you want to have a high vanishing point like this. From this view, with the horizon line in the middle, using a 2 point perspective approach would work just fine.

This looks super cool! I am awful at perspective, so can't feedback on that, but it looks like a really clean drawing. I can't really tell what scale the box is supposed to be though - I'm guessing super small, and on a shelf? I think your textures come across really well :)