do chess bots have favourite openings

Usually chess bots are either told to play a specific openign against another bot (to get unique games) or the bot is programmed with an opening book (a book of moves which it can play in the opening) and it can have multiple choices against a move.

If you'd like to train your opening theory i would use chesstempo opening trainer. if you want to play games in your specific opening choice, i would reccomend just starting a game in a set position perhaps at the start of the french defense.

You could probably have more success on finding bots on lichess.org bot page too

Use the “Finish vs Computer” function.

You pull up one of your games and forward to that set position then pull the up the function.

Ill do that when I want to review a line say against an Alapin or London.