I want to build a planet (or satellite) that:

• is smaller than Earth,
• has a thicker atmosphere than Earth but breathable,
• has neither intense volcanism, nor any extreme condition of that sort that would increase atmosphere density,
• revolves around a binary star similar to BY Draconis

A higher gravity makes for a higher atmosphere density. If feels like this is the best option in order to keep the planet a peaceful place, hence my question.

Question:
How is that possible? Is it coherent in such a system with at least two (small young) stars?

Bonus questions: What would the stellar system be like? Would the other telluric planets in the system necessarily look the same? Would there still be gas giants?