I moved from Moscow to Paris a year ago, and I think Moscow is a success story of fixing traffic.
* Make streets in the center narrower, remove 1-2 lines and make sidewalks wider;
* Remove parking slots, make the remaining ones very expensive;
* No barriers to taxi aggregators or car sharing, just regulations on hours of work;
* Improve public transport (new metro lines);
* (Optional: pave the sidewalks with tiles (Собянинская плитка). Despite bad jokes it really feels nice vs old broken asphalt)
The city became pleasant to pedestrians, traffic jams reduced a lot. Before that I even refused to use taxis, because the price was high, quality was low, and sitting for 1 hour just to move 300 meters was usual. I do not drive myself, but taking a taxi there is no brainer - $5 per ride and much faster than before, without traffic.
Now Paris reminds me of Moscow in the 2000s. Often narrow sidewalks where even two people find it difficult to walk past each other, parked cars that make this difficult even for one person (good luck with baby carriage!). This is not everywhere, not on the main streets, but Paris is an old city and there are many old narrow streets. Those should be made completely pedestrian or keep just one line.
Before the confinement I lived near Petit Champs/Chabanais streets. They made Chabanais and one part of Petit Champs pedestrian, and removed 1.5 lines from another part in favor of sidewalks. Local activity thrived, children were playing, cafes full of people on the sidewalks or streets themselves. I used to joke that they called Moscow mayor Sobyanin to fix the streets. If they didn't, they should... at least not be afraid of radical measures.
And the measures should be radical so that improvements to pedestrians (or taxis, public transport) are big and more people give up on their own cars faster. Biking and scooters are possible all year around in Paris vs just five months in Moscow, so I'm looking forward to more and more of those changes.
P.S. Paris should also make public transport strikes illegal!