Set the dimensions and position of a shape by using the Size
Specify the exact size, location, and angle of rotation of selected shapes by entering values in the Size & Position window.
Find more shapes and stencils - Microsoft Support
You can find shapes by searching the Microsoft Download Center for Visio shapes. Visio shapes are also created by people and companies outside of Microsoft. If you are looking for some very specific or unusual shapes, you might try non-Microsoft providers such as these:
Featured Visio templates and diagrams - Microsoft Support
This page lists all the templates and sample diagrams available with Visio in Microsoft 365. For each category, there is a button you can click that opens the template or sample with its stencils and shapes—right in Visio so that you can get started trying it out. Click a category name to go to a list of related templates and samples:
Prevent or allow changes to shapes - Microsoft Support
Prevent or allow changes to shape attributes. Select a shape in your drawing. On the Developer tab, in the Shape Design group, click Protection. Select the shape attributes that you want to lock, or clear the check boxes for the attributes you want to unlock, and then click OK.
Draw a shape in Visio - Microsoft Support
You can create your own custom shapes by using the rectangle, ellipse, arc, freeform, and pencil shapes in Visio. If you want to be able to apply fill colors to your new shape, you need to create a closed shape. If you use the Rectangle tool or the Ellipse …
Create a shape - Microsoft Support
Create your shape by using the drawing tools, using shapes from other stencils, or pasting an object from another application.
Align and position shapes in a diagram - Microsoft Support
Choose an alignment direction. Select the primary shape that you want the other shapes align to. Press and hold the Shift key while you select the other shapes you want to align to the primary shape. On the Home tab, in the Arrange group, click Align and select an alignment option.
Resize a shape - Microsoft Support
To resize a 1-dimensional (1-D) shape, such as a line, drag an endpoint to the length you want. To resize a shape by typing a value, on the View tab, select Task Panes > Size & Position, and then in the Size & Position window, type new values in the Width, Height, or Length boxes.
Isometric drawings - Microsoft Support
Create an isometric drawing from scratch, incorporate basic shapes, or use three-dimensional shapes and templates. In this article: Create an isometric drawing from scratch. Use Basic Shapes in isometric drawings. Create an isometric drawing with a template.
Shape basics: resize, format, move and add text to shapes
Get an overview of shapes in Visio with this quick-start guide to selecting, moving, formatting, copying, and adding text to shapes.
Use Wireframe Templates to design websites and mobile apps
Wireframe stencils also have smart shapes, such as a range slider or progress bar, that you can customize with control points and right-click menu actions to modify state, numeric values, or visual styles.