Syntax highlighting
JetBrains Rider highlights fields, local variables, types, and other identifiers with configurable colors. For example, JetBrains Rider syntax highlighting allows you to easily distinguish between local variables and fields in your code.
JetBrains Rider syntax highlighting for C# with default colors looks as follows:

Toggle JetBrains Rider syntax highlighting
Press Ctrl+Alt+S or choose
(Windows and Linux) or (macOS) from the menu , then choose on the left.Use the Color Identifiers checkbox to enable or disable JetBrains Rider syntax highlighting.
Click Save in the Settings dialog to apply the modifications and let JetBrains Rider choose where to save them, or save the modifications to a specific settings layer by choosing this layer from the Save selector. For more information, see layer-based settings.
Configure syntax highlighting
To configure syntax highlighting, you can select one of the default color schemes and then customize it if necessary.
You can also customize each identifier color right from the editor:
See the color scheme settings for the current symbol
Place the caret at the desired symbol, press Ctrl+Shift+A, find the Jump to Colors and Fonts action, and execute it.
This will open the relevant color scheme settings for the symbol under the caret.
Semantic highlighting
By default, the color scheme defines syntax highlighting for reserved words and other symbols in your source code: operators, keywords, suggestions, string literals, and so on. If you have a function or method with many parameters and local variables, it may be hard to distinguish them from one another at a glance. You can use semantic highlighting to assign different random colors to each parameter and local variable.


Enable semantic highlighting
Press Ctrl+Alt+S to open settings and then select
.Select Semantic highlighting and customize the color ranges if necessary.

This will enable semantic highlighting for all languages that inherit this setting from Language Defaults. To enable it for a specific language instead (for example, C#), go to the Editor | Color Scheme | C# | Semantic highlighting settings page Ctrl+Alt+S, clear the Inherit values from checkbox, and select the Semantic highlighting checkbox.