You can create libraries of components (known as Collections) to use in multiple models. These are technically just another sketchup model but when inserted via the component browser they are linked to the ‘external’ component. You can edit the external component and save it, then go to the version in the model and select reload and it will reflect your external edits.
As an example, you could have a house with four rooms. Each room as a component that has been saved to a collection, four different people could work on those rooms and save their work, you could then open the house model and ‘Reload’ the rooms and you have brought all their work together.