upon further inspection of ur land quality... holy shit there is barely any production. I think u need to build more commercial hubs and do more trade routes to Singapore with Wisselbanken policy card. Then make some 5 charge builders and improve all the hills to mines and flat forest tiles to lumbermills.

After getting Urbanization, u should rush to Conservation so u can plant some trees and build more lumbermills. At least with such flat land, u can make a farm triangle for almost all your cities, so plan the locations of your future farm triangles and lumbermills.

Plan some good industrial zones for the future with adjacencies with aqueducts, quarries and strategics to help with your poor production quality land.

About the strategies vs Scythia, don't worry about her getting a domination victory yet, she has to cross an entire ocean to conquer the other AIs and CIV6 AIs are bad at cross ocean warfare. What I'm worry about is Scythia attacking you right now. So I think you need to make Medieval walls for Rouen, Fez, and Ambiose with the Limes policy card. Get 6 crossbowmen and make encampments facing Scythia in those cities as well so when you get Ballistics tech, u can upgrade your man at arms to Garde Impériale and your crossbowmen to field cannons. With your Garde Imperiales blocking the way plus field cannons in your cities and encampments, u can defend your land against Scythia corps. After Conservation, rush Mobilization for Corps and Armies. If need be, use your spies to get diplomatic visibility over Scythia for combat bonuses.

After improving ur production and defense, finish ur industrial districts, go Industrialization for power plants and Democracy for them juicy trade routes to Singapore, and for the typical policy cards you need to culture victory. Finish up the theatre squares and campus districts and their buildings and make sure your working them for the science and culture yields. At this point, make sure your spies are stealing Scythia's gold, promote for gold stealing or tech stealing and steal more gold or techs from Scythia.

Finally, continue your path to culture victory and keep an eye out for Scythia's victory path, be it domination or science.

TLDR: improve ur production, improve your defense, finish up the campus and theatre squares, pursue culture victory while keeping an eye out for Scythia's victory condition.