I have several hiking books that cover the Berner Oberland, but it turns out the free maps and guides at the local Tourist Information office ( especially Kandersteg) are more useful.
For Kandersteg, this website is a good resource:
https://www.oeschinensee.ch/en/wandern/
I recommend hikes 6, 7, and 9, all of which start at Oeschinensee ( haven’t done 8, at least as far as I recall). Take the gondola up to the lake, rather than hiking there from town. That way you will get more time with the beautiful scenery around and above the lake itself.