For Command line
Export Database from MySQL 8.x and execute below command. My exported database name will be mysql.db
$ sed -i s/utf8mb4_0900_ai_ci/utf8mb4_general_ci/g mysql.sql
For Text editor
Open the database file on your text editor and use Find and Replace feature to Find the text utf8mb4_0900_ai_ci and Replace with utf8mb4_general_ci