If you have set your tyres up tubeless, don't assume that you'll never have to make a roadside repair. You'll almost certainly avoid those annoying stops for small punctures from thorns and road grit, but performance on larger holes in road bike tyres is still quite hit-and-miss, as this opinion piece tells.
It's a good idea to carry a pump or CO2 canister so that you can get some more pressure into your tyres. Sometimes the plug just won't hold at higher pressures, so you might need to ride a soft tyre home. Leave it overnight and it will often have set enough to take full pressure though.
If you're going to be far from home and calling out the broom wagon isn't an option, carry tyre plugs or a product like Zot! or Stan's Dart to help deal with larger holes. As a last resort, it's worth having an inner tube with you that you can swap in if all else fails, although the sealant will make this a messy business.
Make sure that the inside of the tyre is free of thorns before you pop it in though, as you may have previously accumulated debris that has penetrated the tyre wall but been dealt with by the sealant. It's worth carrying a tyre boot too, to ensure that the tube doesn't get pinched by a larger sidewall gash and itself puncture.