This forum is about the WR250R, a street-legal dual sport bike that was first introduced in 2008, and never received any updates until it was discontinued in 2021. The WR250F is a dirt-only bike that has been in production for more than 20 years and bears no similarity to the WR250R.
Having said all the above, I am 5'6", had a WR450F many years ago, and never had any problems with its seat height.