How to add the same text to every cell in a column?

Question

Google Sheets

This is my first question here, so don't kick me. I want to duplicate, for example, the value or text from A1 to each cell in column B in the range (1:100). How to do it? I tried to use the SUBSTITUTE and CONCATENATE formulas, but errors keep coming up. According to my logic, there should be a formula of this kind: = DUPLICATE ("a1"; (b1: b100)) or should there be another function here?
UPD. How to automate this without stretching the cells.
Flawless option