Is it possible for clusters to have sub clusters?

[3DTOPO]

New Issue Checklist

• [X] I updated Cluster to the latest version.
• [X] I read the Contribution Guidelines.
• [X] I read the documentation.
• [X] I searched for existing GitHub issues.

Issue Description

Is it possible to have sub-clusters? For instance let's say I have a Recreation cluster. When zoomed out, it shows a recreation cluster. But when you zoom in, multiple campgrounds are grouped in cluster(s) and multiple trailheads are grouped in cluster(s) etc. When there is room, then it shows the sub-groups individually.