Import a large MySQL dump 68GB on RDS instance
You may try to edit your mysqldump file to remove indexes. It's just a text file with SQL statements, so you need to somehow find CREATE TABLE statements in it and remove KEY lines from them (except from PRIMARY KEY). But that can hardly help with the speed because InnoDB index creation is quite efficient and doesn't take overhead time compared to separate index creation after the import.

If you have limited time access to the RDS instance, I would recommend to deploy the dump on your local server/PC (it may take even longer), then make a dump of only smaller tables to apply on RDS separately, then think how to move the larger ones. LOAD DATA INFILE may be not much faster than mysqldump so it's worth considering copying tablespaces (e.g. "cold backup method" here: https://dev.mysql.com/doc/refman/8.0/en/innodb-migration.html ).