You can either search first, then create a filter, or create the filter and then set your specific search terms/scope. The only downside of filters is that they only apply to incoming mail; you can't apply them to already existing mails, but you can use the same search terms as a kind of mask, then use the select all checkbox, then click the link to select all mail that matches the search instead of just selecting all mail on current page/view.
You can do this with filter rules on Gmail:
https://support.google.com/mail/answer/6579?hl=en
This list of Gmail search operators may be helpful in crafting your filter rulesets:
https://support.google.com/mail/answer/7190?sjid=11169181429...
You can either search first, then create a filter, or create the filter and then set your specific search terms/scope. The only downside of filters is that they only apply to incoming mail; you can't apply them to already existing mails, but you can use the same search terms as a kind of mask, then use the select all checkbox, then click the link to select all mail that matches the search instead of just selecting all mail on current page/view.
Hopefully that helps.