The next major version of the Transport Layer Security (TLS) protocol will be available in iOS 12.2 and it can already be tested by iOS users willing to install it. Apple Software Engineer Tommy Pauly says the support for the TLS 1.3 protocol was added right after Apple shipped the first iOS developer seed back in January. An exact release date is hard to estimate, most Apple pundits say that it will arrive sometime during early March and will be announced during a product or service launch event.
Source: https://www.bleepingcomputer.com/news/security/tls-13-support-coming-to-ios-122-enabled-system-wide-in-beta-releases/