Check PulseEffects, it has an UI that allows to enable and configure effects for both input and output. Last I checked, it is on the default repository of many distros.
Your computer mic will be biased towards vocal range frequencies anyway. Components of the voice that are unpleasant are in the upper mid range around 3-4k i think. For smoother voices what you really want is specialised compression to get rid of sibilance (hissy s sound) and plosives (low frequency large air movement caused by b, d, p sounds) from listening to a lot of voice calls recently though I think most machines do quite a lot of this automatically. The key here thou is don't get too close to the mic as it exaggerates these effects.
Not a linux user, but a decent external mic or headset is going to make the most difference here, its largely a factor of the tiny internal mics in laptops. They will also do better with sound insulation, internal are not well insulated from the fan, keyboard etc.
Tone changes can help with audibility. I have a really low voice, it doesn't carry well over voice-chat; I'd push my register up a few notes. But yes, filtering tweety mic sounds from other people would be good too.
pulseeffects is a pretty neat tool for both playback and record effects including a compressor, gater, equalizer, filters, de-sser (can help quite a lot in reducing those sharp S sounds) and more. It has made a lot of presentations a lot more bearable for me, and my relatively low quality microphone in a noisy environment sound a lot better for others.
It only requires pulseaudio (almost all distro's already use it) and is available in most package repositories and as a flatpak.
https://github.com/wwmm/pulseeffects