One could modify the feedback loop of the laptop PSU itself to get lower voltages. One could also get higher voltages however that would depend on the PIV rating of the output diode and the output filter capacitor voltage rating.
The buck boost converter shown here is rated for 5A input current max. Therefore at higher output voltages the max current is far lower than the advertised 3A. The heatsink fixing method is particularly bad and uses an adhesive backed rubber. These have extremely poor thermal conductivity. To do a proper heatsinking job you will have to screw mount the heatsink, requiring a weirdly shaped holder that attaches to the fixing holes.
On the plus side this is convenient as a quick fix low precision lab supply.