Is it possible to trigger a release with another release in VSTS?

That's not a capability at present time, although you could write a custom task using the REST API to accomplish the same thing, or check the marketplace to see if someone has already created a task to do the same.

There are a lot of considerations when you start doing things like this, though. What build are you releasing in your "sub-releases"? The latest one? That build might not be stable enough to deploy. A hard-coded value? That's going to be a thing that people forget to update.

Typically, my approach in situations like this are to break down the releases into different discretely deployable units that have no dependencies on other units. They can be promoted through the stages as necessary. Then, if you have the occasional need to just do everything all together (for example, provisioning a brand new environment), have a "combo" release that encompasses everything. There isn't even a need for duplication with the recent introduction of meta-tasks.

You can try Release Orchestrator extension from the marketplace which adds a task to execute and track progress of multiple release pipelines in Azure DevOps.