Importing 1:1 scale 3D models

Hi guys, I writer you because I have a problem. I would like to ask you for some advice on how to manage asset proportions within Unity.
For my personal project, I need the entire scene to be in 1:1 scale, but when I import the scene into the headest, everything appears smaller.
How can I fix this? Since I worked on Maya using millimeters.
Thank you in advance for your reply.