Not directly possible. You will need to convert to the JSON format that PlayCanvas expects which can be done at runtime (despite being a bit slow) but you will either have to write the converter yourself or port one of the existing ones (there’s some on the forums) to JS.
It be far easier to convert them offline (either by downloading the JSON from the editor or using one of tools) and load the JSON at runtime as shown here: https://playcanvas.com/editor/scene/547080
What can also be done is to have the model (JSON) in your PlayCanvas project not preload until you need it. This can be done by unticking the preload settings in the related assets.
Then you can tell the asset registry to load the model asset which will send an event when it has finished loaded: More can be found here: https://developer.playcanvas.com/en/tutorials/?tags=assets