Hello,
Tls-cypt was introduced in firmware 00.06.05.1 | 2019.11.15 and is currently supported.
How to find it: If you select authentication as TLS/Password, when configuring OpenVPN, you have an additional configuration line Additional HMAC authentication. It provides you a list of settings and one of them is Authentication and encryption (tls-crypt).
Best regards,
Žygimantas