Like in making steel.
https://findanyanswer.com/what-is-made-from-coal
Keeping this in view, what products are made from coal?
Thousands of products are made with coal or coal by-products, including aspirins, soap, dyes, solvents, plastics, and fibers such as rayon or nylon. Coal is an important ingredient in production of products that require activated carbon, carbon fiber or silicon metal.
And oil. All of our plastics are from oil. So we are going to go to zero use of fossil fuels by 20xx then we will have to learn to do without most clothing, much building materials, asphalt roads, much of what makes up our cars, etc., a whole lot of etc.