Turns ratio of transformer not on datasheet
You need to consider more than just turns ratio. The high voltage winding insulation needs to be rated for the voltage you're trying to generate. That's why transformers are rated by coil voltage and VA.
Most designers will be looking at input and output voltage rather than turns ratio. The turns ratio may be slightly higher than the voltage ratio to ensure that rated output voltage is achieved at rated load due to internal resistance and other losses. Note that transformers will usually give a higher output voltage when unloaded for this reason.
The transformer selection process will generally be:

Specify the supply voltage(s).
Specify the output voltage(s).
Specify the minimum VA.
Search the catalogues and find one that meets or exceeds the specifications. Alternatively have them wound to specification.