How to upgrade php version on lightsail instance

Wordpress made recommended to use php 7.4...I've been trying to upgrade my version. I've been searching on bitnami and forums but still not sure what to do when I type "sudo apt install php7.4" I get a :

• E: Unable to locate package by glog 'php7.4'
• E: Couldn't find any package by glob 'php7.4'
• E: Couldn't find any package by regex 'php7.4'

How can I install php 7.4 and activated to use so when I type php -v it will output php 7.4 ?