How to improve security by enabling HTTP Strict Transport Security for your site

Hi Heros

HSTS is the upcoming standard and brings more security. Cloudflare already offers to enable that option.

What would be needed to enable it on a multisite which does not use Cloudflare and also don't want to install an additional plugin as this should be done actually without the involvement of any plugin?

Is there a WPMUDEV Plugin doing that already?

Kind regards
Andi