interface – How to define a graphic board size with Axure?

I am totally new to Axure, so I apologize if my question seems "obvious" to those who are used to using the tool.

I am familiar with the tools in which we install a painting before starting to create something. Currently, Adobe XD is my main bet on this. I went through Axure and I could not find where at least on what size I would start working. So, if I want to create a wired structure for a website (this could be 1920w), how can I limit the area to 1920 to avoid putting content outside of the artwork (our "artboard" on Adobe XD)?

I have searched a lot on Google and Youtube but I have not found this precise answer. I am looking for a tool targeting wireframing (also prototyping) and, for some time, companies have considered Axure as their "little darling", so I decided to understand at least its essential elements , namely the essential to get the product. do it as fast as possible. If you could also recommend me best practices concerning Axure, I appreciate them.

Thank you!