It depends on the data. That's why, again, there's a formula for this definition. I'll try to explain it for you in simple terms.
Data 1: 5 6 7 8 9 9,000,009
In this data set, the biggest number is 9 million over the next data point. This is definitely an outlier.
Data 2: 5,000,000,000 6,000,000,000 7,000,000,000 8,000,000,000 9,000,000,000 9,0009,000,000
In this data set, the biggest number is also 9 million over the next data point. This is not an outlier.
It's not about how big 9,000,000 is itself. It's about where it is in relation to the rest of the data. "Markedly different" is subjective. Being bigger than the other data points, even being 9 million bigger, doesn't necessarily make it "markedly different". According to the definition of an outlier, it's not. Check AI yourself if you don't believe me.