The comment from Cloudways isn't clear about how to implement this, so I'm adding a comment to help others who might come across this, like I did.

To setup a wildcard subdomain, after you have setup the DNS wildcard, in Cloudways you need to add a wildcard subdomain in the additional domains list - e.g. *.mysite.com

You still need to add each subdomain manually to the SSL Certificate screen though, if you have using a combination of subdomains and mapped domains. But if you are only using subdomains in your multisite with no mapped domains, then you can choose to use a Let's Encrypt Wildcard certificate.

You can create a CSR for a paid wildcard certificate without any problem. Following the process outlined here:
https://support.cloudways.com/how-can-i-getdeploy-an-ssl-certificate-for-my-application/

But with a wildcard subdomain.

Let's Encrypt does NOT support wildcard certificates (Let's Encrypt feature, or lack of it). https://support.cloudways.com/how-to-install-letsencrypt-free-ssl-certificate/

Cloudways Team

In wordpress multisite it's quite common that you have wildcard support. Additionally, it's necessary that a mistype such as wwe.mydomain.com goes to www.domain.com. You must fill this gap to have a competitive service.

Sweet! How do we implement it on existing Multisites?

It's very annoying to miss this feature when using the WP Multisite.
I've contacted the support here at the Cloudwaays about this and got pretty automated answer that they will consider applying it in the future. This is criminal :-) not to have by default, since it's one time tweak to the Apache server. What's stopping you from providing the wildcard domain, it's quite standard and as said is causing quite annoyance.

Especially when you come from other hosts where you have been used to this functionality and now it's missing on the Cloudways.