In this day and age if one is a SharePoint consultant, the following are the key aspects they should know:
1) Content migrations from SharePoint 2013/2016/2019 to SharePoint Online
2) Upgrading SharePoint 2013/2016/2019 and hybrid-based environments
3) Creating and supporting items across the entire Power Platform (PowerApps, Power Automate, PowerBI and Power Virtual agents)
4) Converting legacy InfoPath functionality to the Power Platform
5) Performing application migrations into custom Power Platform applications
6) Intranet development, re-platforming and evangelizing the Viva aspects
7) Integrating the needed line of business applications into SharePoint
8) Creating and recommending proper governance for the Microsoft 365 stack