: Download the module file and unzip the folder.

: Studio is included in the "Custom" and "One App Free" pricing plans.

Official Odoo Studio is bundled only with paid subscriptions:

: While not a "drag-and-drop" tool, activating Developer (Debug) Mode allows you to modify models, views, and fields directly through the technical settings menu. How to Install Studio Alternatives

Since you cannot download the official Studio module for Community, these third-party tools provide similar drag-and-drop or visual editing features: