For furnitures I use the interior Essentials addon.
It can seems a bit expensive but you have a lot of models and somes materials for the wall and floor and the tool they have to manage the assets is really useful.
Using this with the free version of blenderkit and you can really create some solid scenes.
Graswald and Scatter do not have trees.
Regarding grass the two main addons are Graswald and Scatter and Grassblade is probably a great option too (although it seems really similar to Scatter)
I personally use Graswald with Gscatter (free addon from the same team) and it’s really good but I think it gets behind Scatter in terms of how fast you can setup your scene. I do not own Scatter so I may be wrong but it works with biomes so you quickly have something that looks good out of the box instead of fiddling a bit more with Graswald.
For the trees most popular are Vegetation and Botaniq.
I use Vegetation and the assests are really good. Maybe a bit much, as they are really dense, they can use a lot of ressources if placed by hand but used with Gscatter it’s a lot more manageable.
Botaniq is really great too, assets are great but a bit inferior in terms of quality. Perfectly fine in most cases but if you do close ups it’s noticeable.
Plus Botaniq has a free version so you can always try and see if it suits you.