maybe
daily

Here it says explorer is ok to use in daily but idk about vote chess
https://support.chess.com/article/648-what-do-i-need-to-know-about-fair-play-on-chess-com

But u had to be a premium member to use it and its only for daily !
You can use it to a certain number of moves then you need to upgrade

Yes, any non-live resources (aka anything not a computer/device) such as a book, database, etc. is allowed in correspondence [daily] play.

Opening databases are allowed in all daily games, from both chess.com and other sites, but not engines that analyze a position. Endgame databases are not permitted.

For no premium members there are another free databases like this: https://www.365chess.com/opening.php

Here it says explorer is ok to use in daily but idk about vote chess
It's OK to look at the opening explorer for vote chess. The more serious clubs consult databases to play book lines and even follow theory from recent master games.
https://support.chess.com/article/441-how-do-i-play-vote-chess
are you allowed to use explorer for daily chess?