That is one area SolveSpace really shines too, but there is no chamfer tool - you'll have to use a boolean to subtract that chamfer.
As discussed in related SolveSpace issue thread, "chamfer" feature could be implemented in same way as "tangent arc" (aka "fillet") already implemented.[0]
[0] https://github.com/solvespace/solvespace/issues/149
That is one area SolveSpace really shines too, but there is no chamfer tool - you'll have to use a boolean to subtract that chamfer.