So I have the data of X variable(number of data is 300), now I want to generate the data of Y variable with following condition:

1. mean of Y is 1, standard deviation is 0.5, maximum is 2, minimum is 0.3.
2. X and Y is positive related
3. As X exceeds certain threshold, let’s say X>500, Y starts to increase slower.

I think Y should be follow certain distribution, but how do I control the rate of growth as condition 3