This is standard reading in 8th grade English Language Arts in many middle schools. There are plenty of commercially available reading guides with comprehension questions and lots of other activities to do with this book.
However, teaching in cash-strapped Arizona taught me to identify free lesson plans and materials.
This resource, Carolina K-12, is absolutely fantastic! Although it's no longer "in-use," meaning teachers are no longer posting new materials to the database of lesson plans, the lesson plans that are already uploaded and available for free download are stupendous! I emailed the administrator and asked for free, editable PowerPoint presentations, and they were -- every time -- promptly emailed to me. I used this database for both Social Studies and English Language Arts LPs, but there's a lot even I didn't have time to look at.
Take a moment to peruse what it has to offer -- it's well worth the time and effort, if you teach Social Studies or ELA.
You can always spend money to teach. I personally love the low-cost materials offered for sale at Teachers Pay Teachers, and a quick search reveals LOTS of Fahrenheit 451 resources for sale AND, what I really LOVE about TpT, these are the ones offered for FREE! There's even a free "escape room" exercise that looks like it would be fun to do with the students.
In addition, as a writer, I came across this short story writing contest called Literary Taxidermy. Authors are asked to write a short story, using the first and last lines from a book. I thought Fahrenheit 451 was uniquely suited for this challenge and what a great way to introduce it to your students!
I turned the contest writing prompt into an anticipatory set you can use to introduce the book.