This command lists the tables within an sql database by decreasing size:
SELECT TABLE_SCHEMA AS `Database`, TABLE_NAME AS `Table`, ROUND((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024) AS `Size (MB)` FROM information_schema.TABLES ORDER BY (DATA_LENGTH + INDEX_LENGTH) DESC Paste it in the “SQL” tab in phpMyAdmin. It won’t modify the database, since all it does is select entries and displays them.
Source: https://chemicloud.com/kb/article/determine-size-databases-tables-phpmyadmin/