If you look at the About tab on Tool -> Index MySQL you’ll see information about space used by your tables.
The three tables you mention, in your system, according to your uploaded metadata, are in the older slower obsolete MyISAM storage engine format.
It’s unlikely that adding the new keys will triple the space used. Usually it adds 30 – 50%. Experience, especially with WooCommerce, shows that the tradeoff of more space for less time is almost certainly worth it.
But, converting your tables to the faster InnoDB format may, in fact, make it look like you’re using more space, due to the way space usage is sometimes reported. If you want to use the high-performance keys you need to do the conversion first.
According to your metadata, you have a separate MariaDB server machine from your web server, and that server has 2GiB allocated to the InnoDB buffer pool. You may, or may not, be able to increase that allocation depending on the amount of RAM available to your MariaDB machine. The metadata doesn’t tell me that.
