An engraved QR code needs recognisable modules, a clear border and enough contrast. A code that scans from a screen does not prove the same design will scan well on wood or acrylic.
Confirm the destination first
Check the link before exporting. Prefer a destination you can continue managing. A subscription QR service may depend on that subscription remaining active. More text or a longer link can create a denser code that is harder to engrave at a small size.
Use vector shapes and a clear margin
Export real vector shapes and clean up overlapping areas. Use closed contours for area engraving. A PNG placed in a PDF is not a vector code.
Leave a blank area around the code, free of text, decoration and cutting lines. A standard QR code needs a margin at least four modules wide on every side. Scale that margin together with the code.
Test size and material together
A dark engraving on a light surface differs from a subtle mark in clear or mirror material. Inspect it in the light where it will be used. Reflections and a busy background can make scanning harder.
There is no universal minimum size for every code, sheet and phone. Make a trial in the final material variant at the desired size.
Scan the physical engraving
Try several phones, the intended distance and different angles. Check that the correct page opens. Enlarge the code or simplify its destination if scanning is unreliable.
Read about area engraving design and engraving contrast in acrylic.