An example of adding vector tiles on leaflet map using mapbox
You need to add mapbox token on line 26 in index.html
Mapbox GL JS API - https://docs.mapbox.com/mapbox-gl-js/api/
Installing Geoserver Vector tiles extension - https://docs.geoserver.org/stable/en/user/extensions/vectortiles/install.html
Publishing a GeoServer Layer with Mapbox Styles - https://docs.geoserver.org/latest/en/user/styling/mbstyle/source.html