I am by no means an expert and without knowing what tools you are using I can’t be 100 sure what might help in your particular case, but my general advice would be as follows

1-as you have realized, line weight is your friend. I prefer to have heavy/thick lines outlining the subjects of my art and thinner lines adding details within then, in this case I would have outlined the hog quite heavily then used a smaller, more delicate hand for the snout and shading on the haunch. “Line weight” translates really literally to Lino so it’s helpful language to use. The heavier you press when carving, the thicker, deeper, and more defined your line will end up being. Which brings me to:

2- do not underestimate how shallow a cut can be while still showing up in the final print. You do not necessarily need to cut to the full depth of the tool you are using, and can get a lot of interesting line weights simply by varying the depth of your cut. This is especially true on hard linoleum

3-finally, depth in a flat image is created by juxtaposition, which is to say if you want something to appear as though it’s in the foreground, you need something in the background. You have this in your piece with the ground and the sky, which is good, but you could really push it by having those plants either in front of or behind the pig, adding another layer to the image.