You can warm up your account by outreaching all the leads that LinkedIn suggests to you as 'People You May Know'. This list can be found on "More suggestions for you" in the 'My Network' tab on LinkedIn. It will scape up to 1000 people at one go
To load this search into your Expandi profile you should follow this guide.
Go to the Search tab within Expandi
Scroll through the list of searches until you see search which says 'People you may know' search
Add a name for the search
Usually at this stage for a search you would be asked to upload a URL, but in this case the system does this automatically for you, so no need to paste anything.
You will have the option to assign the leads directly into a campaign, or complete the search and load it into a campaign from the search tab.
Whether you decide to apply the search to a campaign or not, to complete the search press the Search button.
When the search loads you can use the Filters and Actions and assign the appropriate leads to the desired campaign.