What passive speakers are you going to power with the Amp? If you aren't doing that the Amp isn't what you need.

You need a non-surround Sonos with a Line-In, a Port would be similar to an Amp for that but an Era 100 and line-in dongle would do as well and for less money.

Any turntable will connect to Sonos, it will need a phono-preamp. Internal or external.

There are also turntables that connect directly to Sonos, like a Victrola Stream.

Once connected you can play the turntable on any Sonos in your home.

Speakers are a tough call. Era-100s would work. If you have access to Atmos the 300s would be a big step up. If you just want stereo Fives are excellent and some think they outperform the 100/300 for stereo imaging and sound.

Edited to correct the autocorrect blunders.

If I got a Victrola Stream turntable, would that play through my existing ARC and Sub 3 and (2) SL One’s (in family room)? The existing ones are part of my home theater system with surround sound for my TV.  If they would not play through my existing set up, could I add a pair of Era-100s for the family room and play those wirelessly from the Victrola Stream turntable or would those have to be wired? Would I need an Amp for this set up with the Victrola Stream Turntable?

Could I add speakers for an office in home that would also play from the Victrola Stream Turntable? Which speakers for the office in home would work wirelessly with the Victrola Stream Turntable? Era-100s?

You mentioned access to Atmos, I believe my LG TV is using that with my above family room set up. How else would I add Atmos for other Sonos speakers not part of my family room TV surround sound system? For example office in home Sonos speakers or new Sonos speakers for family room not part of the existing TV Surround sound set up?

The Victrola Stream would play wirelessly through any, any combination or all of your Sonos and any new ones you buy.

You can’t “add” Atmos, you must buy Atmos capable speakers to use it. The Era-300s are Atmos capable.

Thank you very much for your help! I greatly appreciate it!

If I wanted to hard wire the Victrola Stream Turn Table to a Era-300 speaker, what wire connection would you recommend?

You just need the Sonos Line-In adapter and an RCA to 3.5 mm stereo cable. But honestly, the main selling point of the Victrola is it connects to Sonos wirelessly.  If you want a wired turntable, there are better/less expensive alternatives. 

If you want to go wired you’d get a lot more turntable quality for your money by getting a wired-only one rather than paying extra for the Stream’s wireless capability. 

Sonos’ offerings are decent:

https://www.crutchfield.com/shopsearch/turntable.html?&o=d&pg=5&fa=1#&price=750-850

https://www.sonos.com/en-us/shop/pro-ject-debut-carbon-esprit-turntable-black

https://www.sonos.com/en-us/shop/pro-ject-debut-carbon-esprit-turntable-walnut

Crutchfield has good information and support, shop for the best deal but support is important too.

$1300 - Sapphire: https://www.crutchfield.com/p_338STRMSPH/Victrola-Stream-Sapphire-Walnut.html

$800 - Carbon: https://www.crutchfield.com/p_338STRMCBN/Victrola-Stream-Carbon.html

This one would tempt me over the Sapphire if going wired:

https://www.crutchfield.com/p_133SL1500B/Technics-SL-1500C-Black.html

In the Carbon’s price range there are many good choices:

https://www.crutchfield.com/shopsearch/turntable.html?&o=d&pg=5&fa=1#&price=750-850