Here are ten words for extended family members in French.

father-in-law - le beau-père
female cousin - la cousine
grandchild - le petit-enfant
grandfather - le grand-père
grandmother - la grand-mère
male cousin - le cousin
mother-in-law - la belle-mère
nephew - le neveu
niece - la nièce
uncle - un oncle

This video comes from the Lexicogs Getting Started in French course.

To practise these words further, please visit:
https://lexicogs.com/what-are-the-names-for-extended-family-members-in-french/