If you're looking to explore character or model downloading for Roblox, I recommend starting with official Roblox resources and community forums. These platforms often have threads and guides on how to safely find, download, and integrate models into your games.
Roblox itself offers a variety of official tools and a marketplace for users to find and integrate models into their games. The Roblox Studio, a powerful game development tool provided by Roblox, allows for the creation and importation of custom models directly within the software.