Resize the formula or name box in the formula bar
To make it easier to view and edit a long formula or large amount of text in a cell, you can adjust the size of the formula box in the formula bar. To accommodate long names, you can also resize the name box in the formula bar. The worksheet and formula bar work in tandem so that contents of both do not overlap.
1. Adjust the width of the name box left or right.
2. Adjust the height of the formula box up or down.
What do you want to do?
Resize the formula box
Do one or more of the following:

To switch between expanding the formula box to three or more lines or collapsing it to one line, click the chevron button at the end of the formula bar. You can also press CTRL+SHIFT+U.

To precisely adjust the height of the formula box, hover over the bottom of the formula box until the pointer changes to a vertical double arrow , drag the vertical double arrow up or down to where you want it, and then either click the vertical double arrow or press ENTER.

To automatically fit the formula box to the number of lines of text in the active cell up to the maximum height, hover over the formula box until the pointer changes to a vertical double arrow , and then doubleclick the vertical double arrow.
Notes 
You can resize the formula box to a maximum size so that only one worksheet row is visible.

When you resize the formula box, the active cell always stays visible on the worksheet.

A scroll bar in the formula box means that there is more text to view. To activate the scroll bars, click the cell or the formula box.

By default, when you enter text in a cell, it is one line of text with no line breaks, but the text wraps when displayed in the formula bar. If you manually insert a line break in the cell by pressing ALT+ENTER, the line break also displays in the formula bar.

Resize the name box

To adjust the width of the name box either smaller or larger, hover between the name box and the formula box until the pointer changes to a horizontal double arrow , drag the horizontal double arrow left or right to where you want it, and then either click the horizontal double arrow or press ENTER.