Not usually. Most of our kits do not come with a printed build guide in the box. The guides are online and free, and the box points you to them, for example with a printed QR code on Clockstar 2.0.
You do not need a phone to use them. The guides open in the browser on any computer, tablet or phone, and you can print them if you would rather work from paper.
The NASA Perseverance Mars Rover is our most detailed build, and the instructions are long enough that printing them would mean a very thick booklet, so the Rover guide is digital only. It also means the photos can be high resolution and zoomable. If you would rather work from paper, see Printing the Mars Rover build guide.
The Rimac Nevera is the exception. It also comes with a printed booklet covering the build. See Where to find the Rimac Nevera build guide.
Every guide is online and free, whether or not your kit came with a printed copy. The online version is worth checking even if you have the booklet:
It is the copy we keep updated when a step turns out to be unclear.
The photos are higher resolution, and some guides have video you can pause and rewind.
All of them are on the Resources page.