Here is a step-by-step process for adding a jQuery library to Magento 2:
Download the jQuery library file from a reliable source, such as the official jQuery website.
Log in to your Magento 2 backend and go to the “Stores” menu and then click on “Configuration.”
In the left-side menu, expand the “Advanced” section and select “Developer.”
Save your changes by clicking on the “Save Config” button.
Create a new file in the following directory:
In this file, paste the following code:
// your custom code here
Add your custom jQuery code within the function.
Save the file and clear the cache to see your changes take effect.
Note: The file path and the name of the jQuery library may vary depending on the version of Magento 2 you are using.