Yes, 5ft 9 is generally considered tall for a 14-year-old boy.
Here's a more detailed explanation:
Based on available data, the average height for a 14-year-old boy varies slightly depending on ethnicity and other factors, but generally falls in a range lower than 5'9". One source suggests that a 14-year-old boy aiming to reach around 6'0" has approximately 5.5 inches of growth remaining, suggesting that a typical 14-year-old male is shorter than 5'9". The same source mentions that 5'9" puts someone in the 69th percentile, which means that this height is above average.
Therefore, being 5ft 9 at 14 years old puts a boy above the average height for his age group.