Note this information only applies to releases before 18.104.22.1682
The build presets tab (Edit → Preferences → Phoenix → Page 1 → Build) permits the user to alter the default state of a built prim and contains the following options:
Adjust the X, Y, & Z values to the desired default prim size.
Enabling “embed an item into the newly created object” and dropping an item into the window places that item in every prim by default. This feature eliminates the necessity of manually adding a script, landmark, or notecard to the default prim after it is built. In essence, it automates the process for the user.