I don’t think the jeans are doing me any favours.

So, I’m trying to put together a casual dinner fit. Tried both black and white undershirt (keeping in mind I’ll get a better white shirt if I go with this), I probably prefer the black untucked. But I don’t love it. Wondering what I can do better. Idk if it’s the jeans, or smth else, but I would love another opinion or two on this. Thanks heaps in advance.