Easy:
* "Six sick chicks."
* "Extra X's." (Say "extra" as "ekstra")
* "Mix the mix."
Medium:
* "The xylophone's six keys are next to the xylophone's six keys."
* "The fox fix the box."
* "She sells seashells by the seashore. The shells she sells are seashells, I'm sure. So if she sells seashells on the seashore, then I'm sure she sells seashore shells." (This one has a lot of "s" sounds but includes the "x" in "seashells")
Hard:
* "The oxpox was no hoax, but the pox was no hoax, either!" (Play around with the emphasis on the "x" sounds)
* "A vexing mix of toxic x-rays." (Focus on getting those "x" sounds clear)
Let me know if you'd like to try any of these! I'm happy to help you practice. 😄