There is a native social login that you can enable on the Forms 2.0 editor. However, it is very limited and would not meet your needs.
I suggest getting a developer to use the LinkedIn API and Marketo API to do what you want. there are probably a ton of coders who can do this for you.
Thanks Josh for the quick response! While development could be done to integrate with the Linkedin API, we have encountered challenges in getting approval from Linkedin to give full profile access via API. Very few websites have the functionality. I am speaking to Cornell University about their prior experience with "fill in with linkedin", though they have since turned it off.
The challenge is not so much with development as it is with their desire to limit who has access. I would hope that a 3rd party has created a product (to minimize cost of ownership with custom software/integrations) to expedite the integration process.
if anyone has experience with this, would be happy to hear feedback and discuss further. Thanks