Size and aspect ratio:
In the primary logo format a minimum size must be adhered to so that legibilty is retained.
The logo must not become distorted from it’s designed aspect ratio, therefore stretching or squashing the shape and text. If the space is restrictive, the scale of the logo (not the dimensions) must be adjusted to fit.
The only ‘rule’ is that the colors do not clash and that there is a level of contrast (or difference) between logo, typography and it‘s specified backdrop: