This article on the Psyche mission says Lucy's propulsion is to be chemical (in contrast to Psyche's electrical propulsion).
Since the fuel needs to be stored long-term, it's almost certainly a non-cryogenic hypergolic combination like MMH/NTO.
There are a number of proven thrusters using that combination which are used for primary propulsion in deep space missions; another question here is dedicated to figuring out exactly what engine Lucy intends to use, but let us say for sake of argument that it's the Aerojet R-4D. With a moderately large nozzle that thruster achieves 311 seconds of specific impulse. We can apply the rocket equation to work out the necessary mass ratio. I saw another source give 1.68km/s required for Lucy's maneuvers, so I'll use that figure.
$$\Delta v = v_\text{e} \ln \frac {m_0} {m_f}$$
$v_\text{e}$ is 311s x 9.801 m/s2 = 3048 m/s
Thus the log of the mass ratio is 0.5512, and so the initial-mass to final-mass ratio is 1.735.
This requires ~43% of the mass of the spacecraft be propellant at the beginning of these maneuvers. The QA that @uhoh referred to in comments shows that this is towards the high end of tankage ratios for deep space missions, but not unusually high.
R-4D might be overkill for a small spacecraft like Lucy, but most smaller thrusters will have poorer specific impulse, so they might cost more mass in propellant than they save in engine hardware.