I have some 3d models and I want to merge the meshes as one single 3d image in javascript. Is there like an npm package or framework for doing so or something?

I have tried combining the individual meshes of the 3d models like below but they didn't fit in as expected.

sharp('images/hat.png')
  .composite([{input: 'images/face.png', gravity: 'southeast' }, {input: 'images/neck.png', gravity: 'southeast' }])
  .toFile('output.png');

Please what is the right way for achieving this?