Hello guys. I’m new to Audacity and I want to know if this awsome software can be used to improve the mic’s compression, noise gate, equalizer so I can send a better mix to OBS for streaming porpouses.
Thanks in advance and have a nice day! 
Audacity does not apply effects, (like compression & equalization), live.
Audacity is for post-production editing, not live broadcasting.
A quick google check tells me OST supports [u]VST plug-ins[/u]. Is there an OST forum?
There are THOUSANDS of free & commercial VST plug-ins, so try searching for “VST compressor”, etc.
…If you’ve got a good-quiet “studio” and a reasonably-good mic & interface (or a good “studio style” or “podcast” USB mic) you should need little or no processing, but some compression/limiting would be common. And, if you’ve got a bad set-up effects & processing aren’t going to help that much. (Noise gating can be very annoying/distracting if the noise is bad.)
Or in a live setting there are often advantages to a [u]hardware processor[/u]. It’s especially helpful with limiting because it can limit/compress before you clip your ADC. Plus, there is no latency (delay).