How to increase/decrease volume in smaller increments/decrements?
From the look of things Android Nougat has limited options to achieve this, but still a few options exist:
Using Magisk
This method is belived to be ideal for devices running on Android 7.0+ Nougat as is in this case.
Requirements

Magisk
Terminal Emulator app.
Volume Steps Magisk module (recent versions) or XDA link

Proceedure


Install the module by flashing it via recovery or the Magisk Manager app;
Next, open the Terminal Emulator app and type this command: vol_magisk;
Press Enter;
If you used the latest version of the module, you would see some values that you can apply by typing and pressing enter.



*For other android (rooted) versions, please see the workaround in my other post : How can I increase the number of volume levels?*
Edit
For higher Magisk versions (20.4+) find the module here.The default config has media volume steps set to 30, call volume steps set to 10.
However modifications can easily be made by customising system.prop values to your liking and zipping up the repo.
Acknowledgements

Learn to Add More Steps to your Volume Slider with VolumeSteps+

Volume Steps Increase (for Magisk v10+)

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