In the future: Can large scale mining pools overpower smaller mining groups to change Bitcoins current ‘rules’ ?

I’m still learning.. having little software background its a steep learning curve and certainly gaps in my knowledge.

As I understand, changing any core principles of Bitcoin would require a huge consolidated effort of miners to ~ all work on a branched off blockchain? ~ with their new plans..?

While this is described as largely impossible.. what if Bitcoin mining became a monopoly like everything else in the world? Until the a majority of miners were under one umbrella? Would that group not they have full control over how Bitcoin works?

Excuse my ignorance, learning what I can! Thanks

EDIT: Thanks for the comments.. I missed the fact that IF a mining company was big enough to make a change, they would have so much financial stake in Bitcoin that it would only hurt them to manipulate it !