Cathy Duffy’s curriculum reviews are a great place to start. One of the most comprehensive collections of homeschool curriculum reviews out there, her website has all kinds of great search features that let you figure out what you’re looking for. You can filter by age, grade level, learning style, and more.
You can also talk to other homeschool moms, go to homeschool conferences where you can talk to the publishers and thumb through the books to see if they fit what you're looking for, find reviews on YouTube and blogs by homeschool parents, and find reviews on online retailers.
There is so much freedom to choosing your curriculum:
Packaged curriculum sets - these include teacher guides & all subjects for each grade (ex. A Beka, Sonlight, Horizons, Lifepac)
Online courses - these are great for when you're looking for an instructor with specific expertise (ex. higher math or foreign language), you're juggling a schedule that limits your availability to teach (job, caring for disabled child/parent), or your child's learning preference makes online learning a great fit
Subject-based curriculum - this is an eclectic style where you collect curriculum for each subject from different companies (ex. Math U See for math, Rod & Staff for reading, Apologia for science). This works great for when you want more control of each subject to tailor your child's learning abilities as well (ex. they are in 5th grade math, but 6th grade English).
Integrated/unit studies - these are ideal for multi-level learning & helps you maximize your time as all the kids learn together. They incorporate several subjects together while focusing on a specific topic or theme (ex. Five in a Row, My Father's World, KONOS, Beautiful Feet).