Drag file from explorer into frame and have it fit

I like Object Styles, I really do. But until I feel the need for an object style, I prefer to set the Object Style panel to None.

Your project would benefit from a custom Object Style.

Another thing to notice:

Preferences > General > Content-Aware Fit > checked on for Make Content-Aware Fit the Default Frame Fitting Option.

Another nuther thing to notice:

I like having the Auto-Fit button ON at default.

I think the only way to get this to work "automatically" is to pre-assign the fitting options to the frame. You could conceivably do that with an object style. But note that if you want an object style to apply automatically to a graphics frame you actually have to draw with the Shape tool (the one without the X in it) or your graphic frame will instantly revert to the [None] object style