How do I put more detail into my models?

LuckyBoyAK It partially depends on what you're looking to achieve with the models, but generally speaking I'd recommend looking into the attach point system. Using attach points, you can create and attach additional parts to a model, even scaling them down to allow higher resolution details.

You can see some examples of this in Sarah's Patreon assets, for example the chains of the lanterns and the leaves/decorations of the kagami mochi.