creating index on READ database (no replies)

Hi,

I am having Read and Write database MySQL innodb_version 5.7.17.

data is inserting data directly into Write database and afterwords, data is replica to READ database for each 2 sec using AWS cloud process.

here my qiestion is, in Write database, my team is not expecting to create index on my requested COLUMNS.

then is there any possibility to create in READ database ?