How do I get the max N numbers in row in Excel?

MAX will take a range and tell me the largest number. But what if I wanted to iterate over that range and find the largest two numbers in a row?

For example, if I have the range [0, 2, 5, 6, 9, 3, 8], MAX is 9, but MAX2 is 15 (6+9). MAX3 is 20 (5+6+9).

How would I write MAX2, MAX3, or MAXN in Excel?