Yes, you can get a department change from a BS course to a BTech course at IIT Kanpur. The 2 most important things to consider during branch change are
There is an additional criterion that comes to play rarely but one should be aware of it. This is
because Students are not allowed branch change if the strength in their parent department falls below a particular number (usually 55%).
Let me explain this to you with an example. If a student wants to change their branch from Earth Sciences to Physics and fulfills all criteria; the CPI and availability of seats in Physics yet, if the strength of Earth Sciences falls below 55% his branch change application will be rejected.
So these are some important points to consider before applying for branch change.