Did Lamarck believes that giraffes came to have long necks through stretching their necks?

Lamarck believed that acquired traits could be inheritable. So as each generation voluntarily extended their necks, their genetics changed, allowing them to have offspring with their necks already that length.

On the other hand, Darwin would have said that the genes mutated on their own and that shorter giraffes would be unable to reach enough food and die. The rest would in turn live to pass on their beneficial genes for longer necks.