Scale Obect or group of objects base on two reference points (similar as in CAD)
This is useful when you need to exactly match the scale of two objects or especially group of objects. Say you have changed the scale in one file but have received a new file from a client that is in the original scale. You want to quickly match the scale change. If you have at least one reference line that hasn't changed, you can pick two reference points on the new object(s) and then the two matching points on the scaled file. This matches the the scale exactly. This can also be used in many other ways.
There are multiple ways to achieve this in Illustrator right now.
The most straightforward is to use Rotate and Scale tools with Smart Guides on, Snap to Grid off, and holding Ctrl to aim to points, as the first GIF shows.
Then, there is the Orient Transform plugin from AstuteGraphics: https://astutegraphics.com/learn/tutorial/orient-transform-tool-subscribe
It’s a paid tool, but it simplifies the workflow, as the second GIF shows.
For some cases you can clip the art to a shape and resize this clipping group to match the scale you need and unclip it.