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There are several such possibilites.
If you really want to specify the weekend is a four day one you can say weekend de 4 jours. From the site Tout pratique.com:
Possibilité d’un weekend de 4 jours
Le lundi de Pâques tombant le lundi 22 avril, le salarié peut demander à prendre le vendredi 19 ou le mardi 23 pour bénéficier d’un weekend de 4 jours.(Quels sont les week end et jours de congé en 2019)
Faire le pont is also a possibility, it means to take the day(s) off between two holidays or between a holiday and a weekend. Definition in the TLF:
Faire le pont. Chômer un ou plusieurs jours ouvrables, situé(s) entre deux jours fériés (ou entre un jour férié et un week-end); avoir ce congé de quelques jours.
Un long weekend is a long weekend that's made possible because of a bank holiday connected to a weekend. It lasts a minimum of three days and must either start on the Friday or end on the Monday.
Un long week-end ou longue fin de semaine est un week-end prolongé en raison d'un jour férié et composé d'au moins trois jours, débutant un vendredi ou/et se terminant un lundi. (Wikipédia)
When two bank holidays happen to occur in the same week or around the same week-end, for example the first one on Tuesday and the second one on Thursday, using two vacation days lead to a seven days break which is often called a viaduc.