import datetime as dt
import panel as pn

pn.extension()

date_range_slider = pn.widgets.DateRangeSlider(
    name='Date Range Slider',
    start=dt.datetime(2017, 1, 1), end=dt.datetime(2019, 1, 1),
    value=(dt.datetime(2017, 1, 1), dt.datetime(2018, 1, 10)),
    step=2
)

date_range_slider

date_range_slider.value

str_format = pn.widgets.DateRangeSlider(
    name='Date Range Slider',
    start=dt.datetime(2017, 1, 1), end=dt.datetime(2019, 1, 1),
    value=(dt.datetime(2017, 1, 1), dt.datetime(2018, 1, 10)),
    step=2,
    format='%Y-%m-%d'
)
str_format

pn.Row(date_range_slider.controls(jslink=True), date_range_slider)