I was wondering if you can transfer your PC files of RCT3 to the iPad/ iPhone app like on roller coaster tycoon classic. Thanks

I am not sure, but I highly doubt it. It likely requires different file formats. Also since the app is only available on ios and you need to go into app files to transfer files you would need a jailbreak which would give you root access however this voids the warranty of ios devices meaning if you have to replace or repair your device and it is jail broke you will be denied. It also means that if you mess up the files when transferring you may brick your device. Also you can only jailbreak any device bellow ios 11.3.1 for the time being as jailbreak uses bugs in the system to bypass security features so your device will be vulnerable to security issues and you would have to be on an outdated version of ios and if you did brick your device you would have to restore if to factory defaults using itunes which would update your device causing you to lose your jailbreak. In conclusion it may be impossible and if it is possible it risks the security and warranty of your devices and have not updated your device since May