xtls is a convenient C++ abstraction library for TLS, which does not do any crypto on its own but is built in an extensible way to allow implementation using various TLS libraries. Currently, there are three built-in backends: OpenSSL, wolfSSL and MbedTLS, and it's relatively simple to plug in your own TLS backend.
Apart from that, this library has some optional things, such as a full blown TlsSocket class that lets you create a blocking TLS client with a few lines of C++, as well as an async version of TlsSocket that utilizes the Arc async framework.
Example usages can be found in the examples directory