We have used 3 person tents for decades. In general they fit two adult people with a little wiggle room. None of them we have used and I’m talking several brands and models, have ever been roomy enough to add a golden retriever mix. The REI halfdome 4 might be roomy enough. We fit our Cairn Terrier fine in that tent but really had to squeeze him into our Hilleberg Kaitum 3. A Cairn is much smaller than a Golden mix.

Some Tarptents are fairly roomy. I’d look at the specs especially the square footage and layout of the floors if you can’t view the tent in person.

Some models change from year to year.