Will apple reject app if there is trial version?
If you come out with “this is a trial” you will likely be rejected. If your app is “we do this and this” and if you want extra Y - try that, too and then decide to pay or go back to just “this and this”

If the app does something significant like Microsoft Word or Omni Graffle and then allows you to buy up to subscribe monthly / indefinitely or one time purchase an unlock to added functionality like editing a document, you should be totally in the clear - especially with one time / non consumable IAP entitlements. 

Basically, the app can’t be trial after the 5 days or whatever. The key for your design is that the reviewer can clearly see some functionality that will always work for free. If your app has no long term utility past the trial, you will need an alternate model or design in all likelihood.