Will my plan increase with the fiber installation?

Depends on what service you have now. The speed tier and what your currently paying to what fiber internet speed your moving to as their are six different speed tiers at six different price points.

The more information you provide the more concise the responses can be.

Allow me to elaborate for why I am asking. A salesman/at&t individual stopped me at my home and asked whether at&t could remove old lines. I'm fine with this, so long as they don't use this as a way to install new lines and then surprise me with an

invoice or the need to pay in anyway for new fiber, which at the moment is not a necessary concern of mine.