What format are the files? MP4, 16-bit WAV?
You can show clipping in multiple Audacity tracks using View > Show Clipping….
If the files are clipped, Audacity cannot correct that unless the files are 32-bit float WAV or AIFF, which is unlikely. You may be able to fix minor clipping in an MP3 too. Clipping in such cases can be fixed when using Effect > Normalize… to perform volume adjustment.
If other types of files are mildly clipped you can try Effect > Clip Fix… before making a final volume adjustment on them.
For some more convenience, rather than import files into Audacity manually, you can add Normalize to a Chain then apply that Chain to a folder of files that you want to process. But you would want to be sure those files were not clipped, because as above, Normalize won’t fix clipping distortion for most files.
Also note that Normalize only adjusts the highest peak in the track to be at the volume you request. It does not make tracks sound “equally loud”.
If you want equal loudness, try this Nyquist plugin ReplayGain plug-in that uses a similar algorithm to ReplayGain. Make sure you get the “New Version” in that post. See here for how to install Nyquist plugins: Missing features - Audacity Support.
If the files are not clipped, you could similarly add that replaygain plugin to a Chain and apply the Chain to a folder of files.
Gale