The term you are looking for is "parametric". You might be able to find a design you need through the many 3D printing file sites using that term. FreeCAD and Fusion360 are open used but another is OpenSCAD if you are more programming savvy than modeling savvy. There are plenty of recipes for threads in there to make your relatively simple design request here.
Tons of good and free options, you just gotta pick which one looks easiest for you.
I was informed about Kagi through one of the posts here and tried it out. It's quite amazing how much better it is compared to even DDG. I didn't mind DDG but it felt "old" but Kagi seems to prioritize user experience over everything else. It may not be free, but it's worth the cost for me.