Yes, you can set up your iMac to store your profile files, such as Downloads and Documents, on an external drive to save local storage. 

Here’s how to do it: 

--- ### **Option 1: 

Relocate Individual Folders (Documents, Downloads, etc.)** 

1. **Connect Your External Drive:**   Ensure your external drive is connected and formatted properly (preferably as APFS or Mac OS Extended for compatibility with macOS). 

2. **Create Folders on External Drive:**   On your external drive, create folders named "Documents," "Downloads," etc., or similar as needed. 

3. **Move Existing Files:**   - Open Finder and navigate to your `Documents` folder.   - Drag and drop the contents to the new `Documents` folder on the external drive. 

4. **Redirect Folders to External Drive:**   

- Open Finder and go to the **Home Folder** (shortcut: `Shift + Command + H`).   

- Drag the `Documents` or `Downloads` folder to the new location on the external drive.   

- When prompted, confirm that you want to redirect these folders.   Alternatively, you can create symbolic links to point macOS to the external drive's folder:   

- Open **Terminal** and use the command:    
```bash     ln -s /Volumes/ExternalDrive/Documents ~/Documents     ```  
Replace `ExternalDrive` with your drive's actual name.

 --- ### **Option 2: Use iCloud for Optimization** 

1. **Enable iCloud Drive:**   Go to `System Settings` > `Apple ID` > `iCloud` > Turn on **iCloud Drive**. 

2. **Optimize Mac Storage:**   Under `Options`, enable "Optimize Mac Storage." This keeps local storage free by storing less-used files in iCloud. 

3. **Combine with External Drive:**   You can still redirect folders to an external drive for a hybrid approach. 

--- ### **Option 3: Change Default Save Locations for Apps** For apps like browsers or document editors: 

1. Open the app settings (e.g., Safari, Chrome, Word). 

2. Locate the **Downloads** or **Save As** section. 

3. Set the default save location to a folder on your external drive. 

--- ### **Important Notes:** - **Keep External Drive Connected:** macOS will expect these folders to remain available. If the external drive is disconnected, you may experience errors or issues. 

- **Back Up Regularly:** External drives can fail, so ensure you have a backup system in place (e.g., Time Machine or another backup service).

- **Format Appropriately:**
The external drive should be formatted for macOS compatibility (APFS or Mac OS Extended).
You can format it using `Disk Utility`.