You have to write custom visual force page to achieve this kind of functionality. Salesforce does not support to view excrete of data or visible only some selected lines. You can create a custom field and populate the n (number of lines) lines from long text field by creating trigger.
Full Answer
What fields should be removed from a Salesforce form?
Any of the “out of the box” fields that come with Salesforce that are not utilized by your company (i.e. No. of Employees or Annual Revenue on Leads) pull off the page. If you keep them there Users will feel obligated to enter something and slow down data entry. As aforementioned, we want to remove all fields that have no value to the User.
Should fields be on the page or page layout in Salesforce?
However there may be some fields that Salesforce requires to be on the Page Layout but may not support your business processes (e.g. Case “Priority”, Opportunity “Probability %”, etc). In those cases my suggestion is to bury the fields as low on the page as possible.
Is there a better way to validate leads in Salesforce?
A better solution might be to use a Validation Rule that requires at least one of the fields to be filled in before the Lead record can be saved. Any of the “out of the box” fields that come with Salesforce that are not utilized by your company (i.e. No. of Employees or Annual Revenue on Leads) pull off the page.
How to prevent other users from sharing files in Salesforce?
You have files shared to other user or group, Salesforce offers a function not to allow other users to share it. There is a box in file sharing setting called "Prevent others from sharing and unsharing", tick this box to enable it.
What is the visible lines in text area long in Salesforce?
# Visible Lines refers to the number of lines displayed for input (before scrolling) on the New/Edit page. As such it helps control the layout of the form and hints to the user how much data can be entered for the "normal" use case.
What is visible line in Salesforce?
# of Visible Lines is the number of lines you see when you are in edit mode. In simple view mode, you will see the complete content of the field. Using standard Salesforce, its not possible to see limited lines in detail(view) mode as Detail shows complete information.
What is rich text Area in Salesforce?
Knowledge article rich text fields provide additional functions, such as the ability to view and edit the source HTML, support for more HTML styles, and smart links between articles. Some features have rich text editors across Salesforce Classic, Lightning Experience, and the Salesforce mobile app.
How do you make a long text area required in Salesforce?
The long text area required attribute is missing while creating the field but you can set the field as required from the page layout by clicking on the wrench icon and checking the required attribute.
Use the Transient Keyword
Use the Transient keyword to reduce the amount of data that needs to be persisted between the server and user. Transient variables are instance variables that aren’t able to be saved. Keep in mind that static variables are automatically transient and aren’t transmitted.
Return only the Minimum Data needed
Modify SOQL queries to only need the fields and objects that are actually being used by the visualforce page.
Refactor and Simplify the page
Minimize the number of form elements and visualforce components that are on the page. In almost every case that I have had issues with the view state being too large interally, the problem has been related to apex:repeat components and the apex components that are nested inside.
