They are often a last ditch effort at offsetting dead bedrooms, relationship problems, or other significant issues and they are often a cause of severe dating stress on you, your primary, and your secondary/tertiary/etc partners.
If you do want to absolutely do it, don’t do it via a mainstream app or don’t do it as a relationship—keep it as a hookup. But, if you insist this is good for you, instead join some sort of tight-knit community that is more open to such alternative relationship styles or you’re going to have a bad time. A really bad time.
In my extensive experience, of those who are open to open/polyamory are either doing it themselves or have serious issues with self-image and/or mental health. Of those who aren’t in these camps, the stress of the relationship dynamics will end up in hurt, pain, and a never-ending conversation about the situation or the lack of separation from the primary.
Again, keep it to hookups or tight-knit pro-open communities and away from those looking for something normal or stable. It’s not fair to anyone involved.
If it’s “working” for you via those mainstream dating communities, you’re either missing/ignoring the issues or you’re in a very tiny minority.