A similar question has been asked before, namely How to force Vivaldi to reload page on start - but it only concerns the lazy loading feature, i.e. loading a tab content only after it has been activated.
With this setting deactivated, Vivaldi will load all tabs immediately after startup. The problem is, it reads the pages from some mysterious cache instead of querying the respective addresses (i.e. fully reloading the pages). The reason I'm saying "mysterious" is because I have no idea how are the pages cached, since many of the tabs that get reloaded this fast way are wildly out of date (on the order of hours if not days).
I would like to set the browser to perform a complete reload of all the tabs - is this possible in the current release of Vivaldi?