The fact you used the phrase rare earth materials is a sign you've been reading oil industry propaganda.

Make a habit of reading mining.com and read about actual rate earths. You'll quickly learn they are somewhat substitutable. By experimental copper electromagnetic.

And aluminum can substitue some copper applications.

And copper can substitue some silver applications.

Yes there will not be enough copper to transition, but with sociological change, degrowth, and technologic substitution it is possible to support 10 billion people.

Dropping the world's population isn't going to help much, you know it ain't going to be poor people who barely register in terms of climate change getting starved off first. Thankfully it is our consumption and economies that have outgrown this world, not the population of humanity itself.