Use the text block's alignment setting when copy on an event page should be centred. You do not need to change the grid width or add custom CSS for ordinary text alignment.
Centre a text block
Open the event page while signed in as an organiser and select Edit Page.
Select the text block you want to change.
Open Properties. Under Typography, find Text Align and choose the centre alignment button.
Review the result at desktop and mobile widths, then select Exit Page Editor when you are finished.
If the text still looks off-centre
Confirm you selected the text block itself rather than its parent container or grid.
Some pre-built components have a component-specific title or intro alignment setting. Use that control when it is shown instead of the general typography setting.
Check the parent container or grid for uneven spacing, alignment, or width settings.
If the event uses custom CSS, check whether it overrides the Page Builder alignment.