Here's the list of duties, that ICO agency can generally help you with:

• Product Development & Advisory
  
• Platform & Technology DevelopmentPlatform & Technology Migration (if you already have a platform / technology developed)
  
• Legal & Compliance Advisory
  
• Whitepaper Writing
  
• Whitepaper Design
  
• Smart Contract & ICO Coin Development
  
• Digital Marketing
  
• PR / Press (different than digital marketing)
  
• ICO Pre-Sales Management
  
• ICO Community & Investor Relations
  
• Bounty campaign management / costs
  
• Listing fees / posting fees
  
• Escrow & Custodial Advisory
  
• Distribution & Treasury Management
  
• Security Audits

You can also google it by words "ICO marketing agency" "ICO marketing provider"

There're really lots of such agencies now, check agency list on ICObench, for example