Advice on a business plan

Hi guys,
I tried to search for a similar topic but could not find anything yet.
I am a full stack developer who start coding here 5 years ago.Currently I am working as a front end developer and I want to start my own job.
I would like to create small websites for local business owners around me but I dont wanna do it with Wordpress or Wix anything like that.
I still want to create those websites by my own.But I am confused at this point.
What should I use for a small business website ? I see that most people want an admin panel for managing blog posts and photos of their website.
So my question is :
Should I use React or Next.js for this or I should use HTML+CSS ?
If I create an admin panel server and If I use that server to change content of different websites, would that be a stupid idea ?
Please suggest if that plan sounds wrong or if you have a better idea.