If you buy a certain network, like paramount plus ( cbs) you can normally get basic which has commercials or pay extra for none or few. Regular live network programs abc nbc cbs have commercials , no different than over the air. If you talking about streaming services with multiple scheduled channels like Hulu youtubetv sling etc then no , commercials are also there. It’s really just like cable tv. You pay for access to the channel You can of course start the program late and fast forward through.
They all have free trials . Try one ( or all) and cancel before trials end . It will give you an understanding of how they work. We use youtubetv as our Sat tv replacement. Along with several pay networks. STARZ hbo etc are commercial free.
Which network are you wanting to stream ?