Ser vs estar

Hola Kaitlin C.

Thank you for your question!

In this sentence, ser is used because the speaker is describing the company's inherent characteristics at the present time: it is small and new.

Although the company may grow in the future, at the moment those qualities define what it is, rather than describing a temporary state. That's why es pequeña y nueva is the natural choice.

We would use estar if we wanted to describe a temporary condition or state.

For example:

So in your example, ser is appropriate because pequeña and nueva are being presented as characteristics of the company, even if they may change in the future.

Saludos

Silvia