Social media set-up and plan to support my business please

Seeking support in setting up (from scratch) a social media presence to support the launch of a new business. This will require:

1) identifying all the right platforms, and the approach to each (i.e. what sort of content to share on each to drive engagement)
2) understanding how they can be managed an measured (i.e. analyse what content is effective and well received, shared)
3) setting them up with my business credentials, and sharing some initial content (which I can provide)
4) setting out a very high-level weekly / monthly / seasonal plan for their management (i.e. when to post, etc.)

Any other advice welcome - I look forward to hearing from you!
Best,
Tom