It’s hard, but worthwhile. Something like the Sharepoint you should expect to have to communicate maybe 20 times, and a lot of them need to be at decision points.
If you can get something to one-click email contents from the SharePoint page, that also points back to it as the source of truth, that will help people get used to it. Don’t just copy-paste from it yourself.
As far as people, I second that you need to figure out what you can successfully mandate or have someone else mandate, and what you need to bring about via consensus.
It also helps to estimate how much time you have to make an effective change in each area. E.g. some things you can push through with some initial energy in your role, that will be really hard later. Others you can build towards over 3-12 months without giving too much power to the status quo. If you have a lot of different projects in this area I’d actually list these out and put a number on them, to help you decide how to proceed or who to ask to help.
Build consensus by bringing people into what you’re doing from most to least excited/sympathetic. Refine your document/processes based on their feedback and it’ll be more palatable to the lazier or more hostile users later on.
Commit to spending personal time with anyone who seems like they are resisting it because they’re genuinely too busy, stressed or confused. Nobody gets left behind in the change. That attitude will be noticed by others and benefit the whole organization overall.