Your thinking of the wrong resistance bands: here look at this link
Yeah you can tell they’re not strong bands due to the width and thickness barely changing across the bands. I have ones similar to these for doing some glute med exercises, but they’re not heavy.
What you want is one’s like this that get wider as the size goes up, which is what makes the tension harder. Like these (not sure if these ones are actually good, but the ones that have the same colours are all made in China in the same factory likely, and then just branded)
https://www.amazon.com/LEEKEY-Resistance-Band-Assist-Bands/dp/B07DR9BT5G/