Example for ReadOnly as TRUE in transaction management could be as follows:

Consider a scenario, where you have to read data from the database. For example, let us say you have a customer database, and you want to read the customer details such as customerID, and customername. To do that, you will set read-only on the transaction as we do not want to check for the changes in the entities. 

https://www.baeldung.com/spring-transactions-read-only