When you want to expand on a topic or provide more detail, a common phrase to use is "elaborate upon". However, there are several synonyms that can be used to achieve the same purpose. For example, you could choose to "expand on" a topic, which implies that you will be providing more information and details. "Clarify" is a good choice if you want to emphasize that you're providing additional information to make something more clear. "Provide more details" is another straightforward option that simply states your intention, while "go into depth" implies that you will be discussing a topic with a lot of detail.