It may be possible [
project Starshot] to accelerate very tiny probes to about 20% the speed of light, allowing them to zip by the Centauri stars/exoplanets in about 21 years.
If we could reach speeds near the speed of light we can go great distances due to time dilation. But the energy needed for this is way beyond our abilities.
If we could travel at, say, 78% the speed of light, we would get to Proxima Centauri in 7.8 years, but this ignores a few years for accelaration/decceleration. The extra energy needed for this is about 2x the normal energy since the travelers/ship would have about double the relativistic mass.