Midi 1u "legato"

Hello! I’m new here and new to eurorack. I’m considering a midi 1u to pair with my atlantis but I have some questions about portamento. This might be a slightly stupid question but if anyone could clear this up for me I would appreciate it.

The manuals state that portamento is available and can be toggled on or off, as well as set time. My question is - will note sliding occur for every note pressed or for notes played “legato” (playing or sequencing overlapping notes)? And if I’m pairing it this way with the atlantis, will the envelope retrigger?

Basically what I’m looking for is the ability to sequence some 303 style slides with midi and having control of which notes will slide and which that won’t.