Trying to Google the question gives about a thousand links to very mediocre sources (mostly companies selling blinds), so I won’t arbitrarily link you to one. But it’s exactly the same mechanism as exterior shutters, just less effective.

Ultimately it’s all about reflecting solar energy away. Some is reflected away by the white colour, while some is inevitably absorbed by the blind making the material hot to touch. The advantage of an exterior shutter is that all the energy it absorbs instead of reflecting is still outside your house, and the window glass should keep it out. Wheras the heat absorbed by interior blinds or shutters is now on the wrong side of your window glass and can warm up the room.

So in order to get the best of the effect, you need nice highly reflective blinds. White is better than darker colours for obvious reasons; you can also get slightly more expensive “thermal” blackout blinds which are coated with pigment that reflects a greater proportion of the non-visible sunlight too.

Also worth pointing out that it’s not binary, and that non blackout blinds and curtains will help too, just not as much.