Honestly, there isn't much you can't do with a decent mid-sized fixed blade (your basic 3-4" Mora type) with a Scandi (flat) grind, and a small axe for processing firewood. With practice, you can also use the axe head for planing and shaving wood (tinder, feather sticks, etc). A 6" knife is completely overkill unless you're also hunting and gutting your own food.
In my experience, a multi-tool has more design compromises than advantages for bushcraft, and I no longer carry one. Folding blades in general are also riskier, in the event you need to do something that stresses the blade, as the hinge is a potential point of failure. A lot of discussions online seem to focus on batoning with a knife, which I would strongly recommend against, in favour of either an axe, or bludgeoning wooden wedges with another piece of wood.
I also used to (and still occasionally) carry a lightweight folding saw, where the blade stows inside the handle, but I also find rare use for it that can't be done with an axe. Those little chain saws that are a piece of serrated wire are little better than gimmicks. I wouldn't carry a sharpening stone for just a few days' trip, but a small stone or lapstone is handy for longer trips. This can be shared in a group.
Beyond those, you could take a hardened plastic trowel for a lightweight digging tool (outdoor shops often sell these), but with your axe and knife, it's also easy enough to shape a pointy piece of wood to accomplish the same job. It mostly comes down to skill with the blades (practice) and creativity in improvising tools and solutions out in the field, rather than bringing everything and the kitchen sink with you.