Hi! So, you need to install a wordpress theme using the CLI for a subsite? Maybe you’re using Cloud Formation to scale your deployment or something and need it done each time your cluster of EC2 scales horizontally? Regardless, there’s a flag for that!
wp theme install blockpress --activate --url=subsite.coresite.xyz
I kept this one short and to the point. This should do it for you. Want to know more? Read the WordPress Docs! Want to read more about my WordPress endeavors? Check this out.