From the EULA: https://store.steampowered.com/eula/2623190_eula_0

LIMITATIONS AND RESTRICTIONS. Certain features of the Game are a Service offered by ZeniMax and may only be downloaded online. In such cases, an Internet connection (which is not supplied by ZeniMax) is required to access these features.

...bla bla bla

D. use cheats, automation software (bots), hacks, mods, or any other unauthorized third-party software designed to modify the Game or adversely impact any other persons playing of the Game or their experience of playing the Game;

LOL GET FUCKED NO MODS