Can upgrade from MariaDB 5.5 to MariaDB 10.3 directly?
The whole jump it is possible (depends on your data structure) but is not recommended and based on official documentation is not supported.

The best option is to perform and step-by-step IN-PLACE upgrade so you will only do a mysqldump before start to backup everything then just install every version and run mysql_upgrade then continue with next version and so on.