SSTP (Secure Socket Tunneling Protocol) carries the VPN inside a normal TLS connection over TCP. Windows has an SSTP client built in, so on a Windows PC there is nothing to install: add a VPN connection, enter the server address with its port, your username and your password.
On Android you can use the open-source Open SSTP Client app, and on Linux the NetworkManager SSTP plugin. iPhone, iPad and Mac have no built-in SSTP client; on those devices WireGuard or OpenVPN is the better choice.
Because SSTP runs over TCP it is usually slower than WireGuard, but it often works on networks where UDP is blocked.