Is that sub domains supported on cloudways digital ocean server?

I have a website that is in HTML and the blog section created in WordPress. I have a server here on Cloudways which is in 10$ plan DO. However, I would like to connect my other website, which is currently on the Namecheap server to here. But, I would like to know this support, sub-domains like as I mentioned above. This means, blog section can be in WordPress s and its website is in HTML format. Is that possible/?

Yes you can.
You will create 2 applications.

Application 1:
PHP Application with the domain name

Application 2:
Wordpress Application with the sub domain name

You have to setup the DNS
Correctly.