Hi gain charlie

The answer your question is Yes, but you need to dig more into the details. To get that you need to define the strategy to follow like if you will have multiple Odoo instances or just one with multiple database. Boths need to have an option config named dbfilter that is used to match the Odoo instance against the databases and normally it's used with this value

^%d$ that means that it will match the db names that have the same name of the domain used to access the Odoo instance. Boths need to have a reverse proxy in front of it pointing to the Odoo instance port but if you have multiple Odoo instances you need to set every domain against the desired Odoo instance port and have the dbfilter in each one to accept the domain to find the database for that domain, normally you will be ok with ^%d$ but you need to create dbs with the same name of your subdomain to match it or just put the db name in the dbfilter like ^greatwall$ to match greatwall.odoo.com

Also you need to point your domain dns to the server that have installed the reverse proxy and you will be ok