Since iOS 14 Beta has only been released to developers and not available on the beta software site on apple as well, iOS 14 is not available to you. But it is possible to still obtain iOS 14 by downloading the beta profile from a third party source (Search Up iOS 14 Beta profile on Safari) then after downloading, give it a few minutes or hours to download. Then restart your iPhone and begin update process. If the update is not popping up, either your storage space isn't enough to download the update(iOS 14 is about 5gb I believe) or the profile you downloaded is counterfeit and not a real beta profile. I have iOS. 14 on my iPhone XS Max right now and it has a few bugs - shuts down and/or freezes sometimes. Here's the source I used to download the beta profile - betaprofiles.com ! Please becareful because there are profile softwares that are mimicking beta profiles and may trespass your privacy.