The SharePoint Column Permission App provides administrators with the capability to hide or set columns as read-only, restricting user access or modification in New/Edit/Display item forms or list views.
(Please note that the Column Permission App is only available for SharePoint modern experience.)
In this tutorial, we will demonstrate how to set up permission parts.
To set up a Column Permission Part in a list, you must have Full Control permissions in the list or be a member of the SharePoint Online group with Full Control permissions.
a. Enter the list where you want to set up a Column Permission Part.
b. Click on Column Permission in the top action bar. (The Column Permission App is unavailable in SharePoint classic experience.)
c. In the BoostSolutions Column Permission dialog box, click Add a Permission Part.
d. In the Add a Permission Part dialog, specify a name for this part and in the Select a User section, specify the users or groups.
If you specify a group, all members of the group will be affected by the column permission settings. Currently, only SharePoint groups are supported.
e. In the Condition section, you can set conditions to decide when the columns should be hidden or set as read-only.
f. In the Set Column Permissions section, select the columns and set them as hidden or read-only for each item form.
If you select columns for the New Item Form, the columns can be hidden when creating a new item.
If you select columns for the Edit Item Form, the columns will be hidden or read-only when editing items.
If you select columns for the View Item Form, the columns will be hidden when viewing an item or invisible in list views.
g. Click the Save button to save the settings.
h. Repeat steps d to g to add another permission part as follows.
i. Click 
to exit the settings page.
If you set up multiple permission parts, users specified in those parts will be affected by all column permission settings.
j. Log in as the specified user and access the list. The content of hidden columns will be invisible to he/she as follows:
k. Select an item and click Edit. The user cannot view the hidden columns or edit the read-only column, based on the conditions.
While the Column Permission App enables you to set columns as hidden or read-only in the list, users may still access or modify these columns in other ways, such as in grid view or by exporting contents to an Excel or CSV file.
The Advanced Settings allow you to disable these features, preventing users from accessing the hidden or read-only columns.
In Advanced Settings, you can decide if the user can access the following features:
Disable "Edit in grid view": If you select this option, the "Edit in grid view" feature will be disabled in the list action bar as follows:
Disable "Export to Excel or CSV": Selecting this option will disable the "Export to Excel" and "Export to CSV" features in the action bar.
Disable "Filter by" on column header or Filter pane: Selecting this option will disable the "Filter by" and "Filter pane" features in the list.
Disable "Gallery view": Selecting this option will disable the "Gallery" view in the list.
Disable "Format current view": Selecting this option will disable the "Format current view" feature in the list.
