Different formatting within a paragraph style

Hi,

A paragraph style is complete, but if you want to have a different font setting, a character style will do it. A character style can change the font family and/or the style, can change the leading, can change the language and anything else you will find in the basic and extended panel of the paragraph style.

• Don't use character styles to extensive. If a whole paragraph is affected, another paragraph style will do this job better.
• Define a character style only with those propertis which are different to the hosting paragraph style properties, so you can use it inside different paragraph styles. E.g. if you have a word in German, you can use the character style with German in any other paragraph style if you do not define other properties.
• You can use character styles manually anywhere you want. But with using manually applied character styles you can use only 1 style on the same text, except if you have an automatic applied character style underlaying from the paragraph style.
• You can use character styles automatically in paragraph styles. Therefore a Paragraph Style has some functionalities to make it so:
  • Drop Initial Characters for the first (specific numbers) of glyphs in a paragraph,
  • line styles, a style per line
  • nested styles (up to or including to a specific glyph, like in your example including 1: ). The style should be prepared before. Nested styles can created according a repeating pattern inside 1 paragraph. 
  • GREP styles, which work according Regular Expressions, like a type and pattern and position of a glyph, followed or following or not following or not follewed a specific pattern, etc.
  • These automatic styles can be used additional on the same text if they have not contradicting properties defined. Any manually applied character style overwrites their properties.
• Character styles can also be applied automatically to text via different functions, where their use is predefined by the user, like cross references, table of content styles, text variables, and others. They are technically applied like the manually applied characte styles.
• Character styles can also be inherited from imported text, like Word documents. You should after importing them work on them, replace by native in InDesign created styles or delete them, as they are often to much.
• Documents converted from Quark Xpress have often Character Styles above every text. Delete them and correct and add paragraph style. That concept of styles is complete different than InDesign's concept.
• Some functions create in InDesign autmatically a character style, like the fuction to automatically create hyperlinks upon text properties.

You can do this with either a Nested Style or a Grep Style

You'll need to make a character style for Bold first

Nested Style

https://helpx.adobe.com/ie/indesign/using/drop-caps-nested-styles.html#:~:text=Create%20nested%20styles.)-,Create%20nested%20styles,-You%20can%20specify

GREP styles

https://helpx.adobe.com/ie/indesign/using/drop-caps-nested-styles.html#:~:text=different%20paragraph%20style.-,Create%20GREP%20styles,-GREP%20is%20an

For the grep style it would be something like 

^.+?\:

then apply the character style Bold that you created