This is an interesting question I've had a little experience with as I transitioned from a career in digital marketing and analytics to digital strategy consulting almost organically as my interests started to grow more towards the running of a business than digital marketing activities.
Firstly, I'd do a lot of reading on digital transformation, which has been a popular buzzword for some time now, but in my opinion a big chunk of that is change management.
You know that saying, "Culture eats strategy for breakfast"? That is especially true when trying to encourage the uptake of digital systems in a workforce that is hesitant or even resistant to it.
Another key thing is customer and user experience - you need to be able to fully conceptualise those using the systems and map out their journeys. People get so hung up on the digital that they forget the real human component needed to make the whole thing work, and whom it is meant to serve.
You need to learn a lot about integrations of different business software - marketing automation, CRM, learning management, finance and HR system software, and the solutions that exist in each of these categories.
Then of course, you can't really completely avoid the digital marketing side of it.
For a good overview of digital marketing and customer value journeys, I'd recommend DigitalMarketer, which is what I use to train my own team, and my coaching clients.
This post is pretty old though so I'm assuming you're a successful digital strategy consultant by now!