Sprinklr, Hootsuite and Synthesio are all partners that may be able to help you here.
You may be able to access webservices/APIs for any of these social Channels and configure a webhook to send them social posts etc...
Have you given a look to ad bridge ? It would enable you to push the lead to media specific campaigns. LinkedIn (Use a Marketo List or Smart List as a LinkedIn audience segment - Marketo Docs - Product Docs) is one of the media natively supported, with facebook. For others, you might need to go through a DMP platform, such a Turn.
I would love to have Twitter, Instagram and other social media platforms to be supported by Ad Bridge.