My question is whether I can stand at a cobblestone farm with multiple accounts and farm them for me. Maybe there's a program or a keyboard shortcut.
AutoMiner with specification on cobblestone with radius 1, AutoTool with restriction Pickaxe
You could get an autoclicker that instead of clicking clicks the mouse all the time and that would automatically farm cobblestone.
Could I then change the tab without it ending?
No, you would have to use another program such as an AutoMiner to do this
You can stand there and hold down the mouse.
Then you press F3 and T while still holding down the mouse.
As soon as the progress bar is about in the middle, you let go of the mouse. CAUTION: You must not hold down the mouse when the reload process has finished.
And tada. You continue to mine the cobblestone without holding down the mouse.