How to extend a 5x3 shed concrete base to 6x4?

Pretty self explanatory really. The old shed I assume has been there for decades (it looked old when I moved in 10 years ago) and is on a concrete base of 5x3 foot. I want to replace it with a new shed that is 6x4, but a quick Google search suggests it is not practical to extend a concrete base and to use 'pads' and decking joists instead. It will mainly store tools and my lawn mower so is not going to be a man cave or anything, but don't want to a slapdash job either. Anyone have any experience of something similar? Thanks

Had a similar issue quite a few years ago, but with a much larger initial base.
Shutter the new size (with a suitable foundation to the addition), and instead of just increasing the size add height to the existing base as well.
Clean and 'slurry' the top surface of the existing base before adding on to it.

Alternatively break up and start again!

I suppose you could drill holes in the edge and resin in some rebar, that would help lock new to old.

Your siply putting a light shed on it.
Most of the shed will be on the old base anyway.

Shutter and lay the extra. Build shed, have a beer..