Hey Leslye,
the portfolio tag archive pages display the projects in the same way as the portfolio page itself, in order to retain consistency in representation (according to the best practices of user experience) and avoid confusion. Technically, it is possible to force all tiles be the same size on portfolio tag archive pages, yet it requires customizing the theme code, namely introducing an “if” criterion into the “large_size_class” function on line 953 of the “functions.php” theme file in order for the function to fire only on portfolio page itself and not on tag archive pages. Such theme customizations are, unfortunately, outside of the scope of the ThemeForest support policy, yet I can recommend Envato Studio and UpWork for high-quality freelance professionals who can implement such a change.
Sincerely,
Andrii / Satori Studio