Can holding down a mouse button be automated?

I would love to be able to scroll down a very long webpage without having to be near the computer. The webpage has several thousand entries and they only keep loading and displaying as I get near the bottom of the list. Putting a heavy object on the space bar doesn't work because it's a JS frame inside a webpage. The webpage is the list of people I follow on **Instagram**, which is reaching the limit of 7500 and I need to get to the end to quickly unfollow and monitor, as I am sure I never manually followed that many people myself. A glitch is making the number of accounts I follow stay the same even if I unfollow accounts (a very widespread issue ). I use a Logitech Trackman mouse on one the 2014 iMac and one of the side buttons is configured to scroll down. However I do not not how to "lock" this button in "pressed" positon (duct tape didn't work). Another computer I have is a MacBook Pro 2019. (Another device I would be open to do this on is an iPhone 13 Pro). I am not finding any ways to do this simply, could this be done with Automator? I opened Automator and looked for scrolling and mouse related functions but couldn’t find anything. I am wondering if I can just record pressing the button down and have the computer repeat it indefinitely or if there is another way to do this. I am open to system defaults, Terminal or Automator scripts, or free third-party options.