That depends on the tankless model you choose.
There are tankless electric heaters that are capable of running all the things you describe, simultaneously. They will, at full load, pull more power than the entire rest of your house.
A tankless heater often requires a significant upgrade to the distribution panel at the very least, as it can draw heavy amps - equivalent to an electric stove, electric clothes dryer and central air conditioning COMBINED at full load, and the wiring and supply installed have to be sized to handle the full load. So in addition to the price of the tankless heater, you also have to factor in the costs of upgrading the power supplies for it.
Tankless electric heaters have regular, non-optional maintenance requirements. You MUST turn it off and de-lime its heating elements on a regular basis, or it will die an early death.
Tankless heaters do not eliminate the wait for hot water at distant faucets. If that is a problem you're trying to solve, a central tankless unit is not the way to do it. A small point-of-use unit installed at the faucet, however, could be - and those don't have the huge power needs the central units do. Some can just plug in at the wall.
For all the costs and hassles associated with tankless units, I don't recommend them. Here and there they have their merits but for the most part they aren't a good enough substitute to warrant the choice. Tank heaters are reliable and effective, and standby losses need not be great, especially if you install supplemental insulation to the tank and insulate the distribution lines.
Good luck with it.