First things first: Ottilie is a deep sage green — muted, grey-softened and slightly cool, with an LRV of just 11.3. That's a proper depth of colour, not a mid-tone, so treat it as the room's anchor and build everything else around it.
The mistake people make is pairing a deep, slightly cool green like this with brilliant white woodwork — the hard contrast turns Ottilie flat and institutional. Go for soft, warm off-whites instead. Farrow & Ball Au Lait (LRV 80) is your safest bet — creamy and milky, it lets the green breathe while keeping the frame gentle. Paper III from Paint & Paper Library (LRV 75.3) does the same job with a quieter, stonier cast if you want more restraint. Either way that's a big light gap between wall and trim, so the scheme reads considered rather than stark.
For grounding, Mylands Cigar BH.20 (LRV 11.8) sits at almost exactly the same depth — a smoky tobacco brown that pairs with Ottilie like branch and leaf. Use it on cabinetry, a lower wall or in a study where you want the green to feel rooted.
Fancy a bolder note? Dulux Fuchsia Falls 2 (LRV 29.8) is a bright, cool magenta-pink — close to green's opposite on the wheel — so a small dose against Ottilie is genuinely striking. One piece of joinery, a lampshade, the inside of a shelf unit. Not the whole room.
Metals matter with a colour this muted: antique brass and aged bronze bring a deliberate glow that stops the sage going sombre, where chrome and silvery nickel push it grey.
Practically: at LRV 11.3 Ottilie drinks light, so sample two coats on a big board and judge it in the room's darkest corner, morning and evening. In north light the grey in it comes forward; warm lamplight brings the green back. If the room is short on light, lean harder on the warm off-white and the brass.