For example:
https://bokeh.pydata.org/en/latest/docs/gallery/logaxis.html
If you have a lot of different lines you also have a lot of entries in the legends. It is already possible to mute/hide legend entries. But i think it is not possible to unselect certain entries by default. I mean image you have 30 lines and you want to compare 2 :) So You have to click 28 times to get the view you want, it would be easier to hide entries by default
Actually, this is already possible, you can set muted or visible properties on the renderers themselves:
import pandas as pd
from bokeh.palettes import Spectral4
from bokeh.plotting import figure, output_file, show
from bokeh.sampledata.stocks import AAPL, IBM, MSFT, GOOG
p = figure(plot_width=800, plot_height=250, x_axis_type='datetime')
p.title.text = 'Click on legend entries to hide lines'
for data, name, color in zip([AAPL, IBM, MSFT, GOOG], ["AAPL", "IBM", "MSFT", "GOOG"], Spectral4):
df = pd.DataFrame(data)
df['date'] = pd.to_datetime(df['date'])
r = p.line(df['date'], df['close'], line_width=2, color=color, alpha=0.8, legend=name, muted_alpha=0.2)
# mute the last renderer from the loop as an example
r.muted = True
p.legend.location = 'top_left'
p.legend.click_policy = 'mute'
output_file('interactive_legend.html', title='interactive_legend.py example')
show(p)

Most helpful comment
Actually, this is already possible, you can set
mutedorvisibleproperties on the renderers themselves: