You could also make a metallic or plastic strip, or try using a long wooden craft stick, and attach it to the inside of your boot near the ankle.
You could also wrap a piece of cloth around the ankle if the boots are too tight to accommodate thick socks on your feet.
This will keep your boots standing up straight while you’re not wearing them, so they’ll be less likely to slouch when you put them on. [2] X Expert Source Penny SimmonsShoe Care Specialist Expert Interview. 19 November 2020.
Rigid leather boots or boots with ankle support are the least likely to slouch.