r/Portuguese – (EU-Portuguese) – Is the last “s” pronounced differently depending on the next word?

I started learning Portuguese about a week ago. I’m noticing that the YouTuber I’m watching sometimes pronounces “mas / mais” like “mass / maiss” and sometimes like “mash / maish”.

From what I can tell, it seems to be pronounced mass/maiss when the next word starts with a vowel, and mash/maish when the next word starts with a consonant.

Is that correct? I just want to make sure. And would that also apply to all words ending with “s”?