If MySQL isn't configured to use this then full UTF-8 support won't be available. This means the site won't allow users to include emojis and other recent Unicode additions, they may get an error instead.
The steps to check MySQL is configured for full UTF-8 support is documented. What do you get for these values?
It isn't really necessary to enable UTF-8 support but it's highly recommended. Changing this at a later date is more complicated and quite a slow change.
If the MySQL settings are managed by the hosting company ask them to change the settings as listed in the above documentation. If the hosting company prevent the MySQL settings being changed as recommended for Moodle look around for another company.