How do I adjust opacity of an "image as a plane" in Version 2.90.1? I want to adjust the opacity of an image overlapping another image.
For example, in this image, I have a car overlapping an airplane.
How do I get that same effect in blender?

All the tutorials I've found are very outdated, the UI has changed so much at this point, they can't be followed. Do I have to setup some kind of crazy thing in the shader editor, or is there some simple opacity slider I am overlooking?
I managed to get the image added with transparency, I just can't figure out how to adjust the opacity so I can see through the image.

Edit Finally was able to adjust the opacity without removing the transparency using the suggestions provided, adding a second Mix Shader and Transparent BSDF (for a simple effect, this was not easy for a beginner):
When selecting your image plane, navigate to the image section of the properties side bar and click on the transparency button to enable it, then adjust the opacity to your desired value.

Alternatively, if you are using the add-on version of images as planes, and still wish to see your image in the final render, you can modify your shader like this, and use the &quot;fac&quot; slider to adjust transparency.