How to reduce incremental zooms in leaflet?

Question

I am making maps in leaflet and cannot change the zoom increment for some reason.

I don't have the option to use

var map = L.map('map', {
  zoomSnap: 0.25
});

I also don't have these functions available:

options = leafletOptions(zoomControl = TRUE,
                                        zoomSnap = 0.25,
                                        zoomDelta))

This is my code so far:

map <- leaflet(Reservoir_locations) %>%
  addTiles() %>%
  setView(lat = 52.5, lng = -3.005, zoom = 09) %>%
  addProviderTiles(providers$JusticeMap.asian) %>%
  addCircleMarkers(
    fillColor = "Blue",
    radius = 14,
    fillOpacity = 1,
    stroke = F,
    ~LON, ~LAT) %>%
  addScaleBar(options = scaleBarOptions(
  maxWidth = 300,
  metric = TRUE,
  imperial = TRUE,
  updateWhenIdle = TRUE
))

map 

The resulting map is too zoomed in, but it's too small when I adjust the zoom.

I would like to be able to zoom by x0.25 increments if possible.

Any help would be much appreciated.

Many thanks,

A