I have refer this doc https://www.eventbrite.com/developer/v3/endpoints/events/#ebapi-get-events-search
but I can not identify how to get event list base on tag.
You can search events on this data point by using the events search endpoint along with the format and category parameters. To see more than the category/format ids, use expansions. See documentation here: https://www.eventbrite.com/developer/v3/endpoints/events/#ebapi-get-events-search
The use of tags has been removed. What you see on the web UI that look like a tags, are representations of categories, subcategories, and formats. In your example, you see "Things to do in Colorado Springs, CO," "Race," and "Community." The "things to do" category is automatically assigned based on the location of the event. The other two categories are added manually by the event organizer. It is also worth noting that categories cannot be applied to private events as categories are intended for discovery.
The confusion here stems from language inconsistencies between the GUI and the API. Here are the translations between how these data points are represented on the web UI and the API:
GUI : Event Type, API : Format https://www.eventbriteapi.com/v3/formats?token=XXX
GUI : Event Topic, API : Category
GUI : Event Sub-topic, API : Sub-category