Ansys uses the element size property value as a starting point for the mesh size when Use Adaptive Sizing is set to Yes. The element size property’s value can be specified by the user or determined automatically through using Defaults. You can follow the following link that will give you more clarification on how the default works.
Adaptive size “Yes” doesn’t directly decide the Number of nodes. However, the system automatically calculates the nodes and element sizes depending on your bounding box of the geometry, and physics preference which refines the mesh accordingly depending on the curvature of the geometry.