My colleague had bought this succulent plant for our office in a supermarket, and it was left there before lockdown. Over the months it has grown in size (it had a small rose-like shape just above the ground when it was bought) and now it's not stable; moreover, some roots grew at the base of the stem and others are coming out of the drainage hole of the vase. I wonder: should it be repotted with the whole stem covered by soil? Also, what kind of succulent plant is it?
You can certainly put it in a bigger pot to make it more stable, but don't try to bury all the "bare stem" otherwise it is likely to rot before it grows any roots.
You might want to start some new plants if you don't like the shape of the old one. Carefully pull off two or three of the bottom leaves and put them on a piece of paper in a warm well-lit place like a sunny window.
They don't need any water, because there is plenty of water already stored in the leaves. After a few days they will start to grow roots from the bottom of the leaves. (The reason for putting them on a piece of paper is so you can see what is happening, and to keep them away from damp soil which might rot them before they start to grow).
As soon as the roots are a few mm (a quarter inch) long, put the leaves on top of the soil in a pot so the roots can grow down into the soil. Don't try to bury the old leaf, and don't over-water them!
A new plant will then develop and the old leaf will wither and die.
According to the PlantNet app it seems to be some kind of Crassula, maybe crassula ovata. I have bad experience with burying succulent stems - I think they tend to rot if under wet soil.
You could try pinching off the end, maybe it can develop branches. Or try to root some of the leaves and replace the old plant with fresh ones.