You kind of can. I keep a list of names next to my home portal and when you want to go to a different one you change the name

I have one portal at home that i just change the name when i want to go somewhere else.

I have a portal hub at my main base and I explore in cardinal directions. When I have to sail to a new island I build a new lodge with room for 2 portals on that island one that goes back to the previous lodge in that direction and one for the next island in that direction going forward.

I also have 2 emergency portals for islands that are extra long (takes more then 1 days worth of travel) that go back to the main base so I can sleep and rest. The emergency portals are labeled E1 and E2. The main portals are North, South, East, and West. The 2nd portal in that direction is North 1, the next lodge holds North 1 and North 2 etc.

Everything that the others suggested works nicely enough, so if you prefer to stay vanilla, I would do that.

If you prefer to just mod the game, then I really like Any Portal ( https://www.nexusmods.com/valheim/mods/170 ) and it would be exactly what you want to do.

So you can name one Main Base and link all outside portals to it. And then you can either switch where the Main Base portal takes you each time from the drop-down menu, or you can set up multiple portals.

I don't think they will include such a feature in the base game since that removes some of the struggle, but if not, I'm sure a mod for it would always exist