Read only user

The db version is 11.2.0.4 on linux 6.8

My question is, I have created a schema or user with the privilege to create table, create index, create view and create session and procedures. We are loading data to the tables to this schema. After the data has been loaded, there will be no more changes to the data and will be static. So, after this, we want to make this schema read only even apps or systems and the schema itself should not be able to make change to the data in the table it owned. Is it even possible? If so, how can we approach to do