You can just use ctrl A to highlight all the cells, and resize the row or column, depending on how long or wide you want it to be. Also, sometimes the size of the cell will change based on the font or the length of the object or string in a cell. you can now then just select "shrink to fit" for your object or string to fit in the box or cell you put it into.
For more tips on excel and financial models
, you can check this out. Hope this helps!