You have two options: Either download models or draw them yourself. AI might provide a third option but I don’t follow that.

For option one, start at thingiverse, it has tons of useful stuff. There are many other sites to explore as well.
<p style=”text-align: left;”>Option two gives you a lot more versatility. Learning CAD takes a bit of effort, but there is a lot of good, free cad software to choose from. FreeCAD is opensource, Adobe Fusion360 has a free version that is quite capable, and there are several others like OnShape and tinkercad.</p>

To produce your own files to 3D print options include;

• Use 3D CAD to design something then export in a file format the printer can accept.
• Use a 3D scanner (to scan an existing item), and associated processing software to fix any gaps or other issues with the scan.  Print the resulting file.

3D CAD in the broadest sense includes software suited to mechanical items, through to other software aimed at more organic shapes, or even animals/people.

I’ve drawn quite a lot of items for people who have 3D printers but can’t draw what they want to print so for your described use it would sit on the shelf until you can produce files for it to print.

Your mention of Toby Jugs would also need a CAD program with more organic shape capability than the majority of engineering based ones that most on here would tend to use which would really only be suitable for a basic jug shape not the face and other features..

Gemini suggests….

3D Sculpting & Organic Modeling

• ZBrush: The industry standard for high-detail digital sculpting and organic character creation.

• Blender: A free, open-source hybrid tool that combines robust polygon modeling, animation, and a heavy-duty sculpt mode.

• Nomad Sculpt: A popular portable sculpting app for tablets.

• Shapelab: A VR-based 3D sculpting tool designed for intuitive clay-like manipulation.