Learn Spanish (Latin America): La casa es más o menos grande.

In this sentence, más o menos is used as a set phrase meaning "more or less" or "kind of." Because we are just describing the house and not comparing it to another building, we do not need to use que.

La casa is feminine. Why isn't the adjective granda?

Adjectives that end in -e, like grande, are gender-neutral. They keep the exact same form for both masculine and feminine nouns. You only change them if the noun is plural (for example, casas grandes).

Why do we use es instead of está here?

We use es (from the verb ser) because the size of the house is a fundamental, permanent physical characteristic. We use estar for temporary states, conditions, or locations.

Can I use más o menos by itself in other situations?

Yes! It is a very common phrase on its own. For example, if someone asks how you are doing, you can reply más o menos to mean "so-so" or "okay."