Theory:

To format the text, many formatting options are available in the format menu. Buttons are provided for the frequently used options in the LibreOffice Writer for convenience. To apply these options, the text should be selected first. After selecting the text, any of the following buttons can be clicked.
 
icons.png
Format options
 
For Bold text - Click B icon
For Italic text - Click I icon
For Underlined text - Click U¯ icon
 
The above commands can also be done by selecting \(\text{Format \(\rightarrow\) Character}\).
 
Keyboard shortcut:
\(\text{CTRL + B}\) keys are selected to make the text bold.
\(\text{CTRL + I}\) are selected to make the text italic.
\(\text{CTRL + U}\) keys are selected to make the text underlined.
Fonts:
A set of characters and numbers in a certain style is known as fonts. Every font is different from the other.
  1. In the Character dialog box, from the Fonts tab, click the down arrow in the Fonts combo box.
  2. To open the Character dialog box, select \(\text{Format \(\rightarrow\) Character}\).
  3. Choose the required font from the lists.
  4. According to the selected font, the text changes.
font.png
Font options
 
Font Size:
The size of the text is also changed for a legal document and advertisement material.
  1. In the Character dialog box, from the Fonts tab, click the down arrow in the Size combo box.
  2. Choose the required font size from the lists.
  3. According to the selected font, the text size changes.
font changes.png
Texts with different font sizes
 
Font Colour:
The colour of the texts can also be changed using different font colours. Even with the help of a colour printer, the text colour can be changed.
  1. The text colour can be changed by selecting the arrow in the Font Colour icon.
  2. After selecting the arrow, a colour palette is displayed.
  3. Any desired colour can be selected from the colour palette.
Or else another method can also be followed.
  1. Choose the desired text to be coloured.
  2. Select the Font colour icon to apply the colour.
Font size.jpg
Texts with different font colours