A large wall hole needs support and a patch of matching thickness rather than filler alone. Before cutting, check for wiring, plumbing, or moisture behind the surface; drywall often uses backing and new board, while traditional plaster may require a repair compatible with the existing lath or base.
Check what is behind the wall before enlarging the hole
Inspect through the existing opening with a light and use appropriate detection methods. Do not put a saw where wiring, plumbing, or ductwork may be present; if the damage came from a leak, repair and dry it before closing the wall.
For drywall, create firm edges and backing
Cut only back to sound material in a manageable shape, add backing strips or use existing studs, and screw in a patch of matching thickness. Avoid unsupported floating edges that crack with minor movement.
For plaster, preserve any sound base
If the lath or base is stable, it can support a compatible patch; loose plaster around the hole needs securing or removal back to sound edges. Do not fill a deep cavity in one layer with material intended only for thin finish work.
Tape, level, and finish in stages
Treat joints according to the wall system, allow drying between coats, and feather the finish beyond the patch to hide the edge. Control dust while sanding and prime before painting when the repair compound requires it.