No. When two or more adjacent polygons are combined, the polygon parts are merged into a single part polygon instead. The images below show adjacent polygons with shared boundaries merged into a single part polygon.
Multipart features are composed of more than one physically separated part and only reference one set of attributes. Generally, multipart features are often preferred to simplify analysis and improve read-write performance. Adjacent polygons have shared boundaries and cannot be merged to form a multipart polygon feature as multipart polygons do not have shared boundaries.
However, a single part polygon with a shared vertex can be merged into a multipart polygon, as shown in the image below.
In ArcGIS Pro, multipart polygons can be created using the Merge or Dissolve tool. The Merge editing tool merges selected features of a layer into a single feature, while the Dissolve tool creates a new output layer of multipart polygons based on common field values.