How to Display Field Values of Records in a Related List

Currently, it is not a standard feature to directly display a field value from Record B (located in a Related List) as a field on Record A.

As an alternative, it is possible to create a Lookup field on Record A that references Record B, and then use a Formula field to display the value from Record B on the layout of Record A. 
If this aligns with your business operations, please refer to the following steps.

※ Note: In addition to the Record B already registered in the Related List, you must separately populate the Lookup field on Record A with the corresponding Record B.

＜Step1: Steps to create a Lookup field on Record A that references Record B＞

1.Click the gear icon in the upper right and select [Setup].
2.Click [Object Manager].
3.Click the object for Record A.
4.Click [Fields & Relationships] on the left, then click [New] in the upper right.
5.Select [Lookup Relationship] as the Data Type and click [Next].
6.Select the object for Record B in [Related To] dropdown and click [Next].
7.Enter a value for [Field Label] and [Field Name], then click [Next].
8.Set Field-Level Security and click [Next].
9.Set the Page Layout and click [Save].

＜Step2: Steps to create a Formula field to display Record B’s field value on Record A＞

1.Click the gear icon in the upper right and select [Setup].
2.Click [Object Manager].
3.Click the object for Record A.
4.Click [Fields & Relationships] on the left, then click [New] in the upper right.
5.Select [Formula] as the Data Type and click [Next].
6.Enter [Field Label], [Field Name], and select the Formula Return Type, then click [Next].
7.Enter the formula to display the target field value from Record B and click [Next].
※ Please select and configure the target field using [Insert Field].
※ Click [Check Syntax] to ensure no errors are found.
8.Click [Save].

＜Step3: Steps to display Record B's field value on Record A＞

1.On Record A, set the corresponding Record B in the Lookup field created in [Step 1].
2.The field value from the target Record B will then be reflected in the Formula field on Record A created in [Step 2].