Ancient China GLs:
https://www.mangago.zone/read-manga/peach_blossoms/
https://www.mangago.zone/read-manga/can_t_get_along_with_dear_princess/
https://www.mangago.zone/read-manga/the_guest_of_the_little_general/
https://www.mangago.zone/read-manga/fall_in_love_with_the_empress_zephyr_scans/
https://www.mangago.zone/read-manga/princess_naihe_is_too_black_bellied/
https://www.mangago.zone/read-manga/slender_waist/
https://www.mangago.zone/read-manga/seeking_a_beauty_in_the_east_sea/
https://www.mangago.zone/read-manga/unaware_his_majesty_is_a_girl/
https://www.mangago.zone/read-manga/ting_shuo_taihou_he_taihou_shi_zhen_de/
https://www.mangago.zone/read-manga/indulging_a_crazy_beauty/ (toxic relationship)
Other GLs set in historical times:
https://www.mangago.zone/read-manga/sayonara_rose_garden/
https://www.mangago.zone/read-manga/the_wind_spell/
https://www.mangago.zone/read-manga/moonlight_garden_kang_unnie/
https://www.mangago.zone/read-manga/opium/
https://www.mangago.zone/read-manga/marie_and_alex/
https://www.mangago.zone/read-manga/living_will/
https://www.mangago.zone/read-manga/oniisama_e/
https://www.mangago.zone/read-manga/the_playgirl_and_the_prince/
https://www.mangago.zone/read-manga/seasons_in_bloom/
https://www.mangago.zone/read-manga/lily_of_the_valley/
https://www.mangago.zone/read-manga/lemon_pie_night/
https://www.mangago.zone/read-manga/getting_to_know_grace/
https://www.mangago.zone/read-manga/grace_of_the_vineyard/
https://www.mangago.zone/read-manga/maison_de_maid/
https://www.mangago.zone/read-manga/ghosts_of_greywoods/
https://www.mangago.zone/read-manga/her_shimcheong/
https://www.mangago.zone/read-manga/maid_in_heaven_1/
https://www.mangago.zone/read-manga/chun_and_alice/
https://www.mangago.zone/read-manga/yuki_and_the_authoress/
https://www.mangago.zone/read-manga/the_song_that_transcends_this_world/
https://www.mangago.zone/read-manga/itsuwari_no_marigold/
https://www.mangago.zone/read-manga/the_noble_lady_on_the_edge_of_the_cliff_wants_to_make_the_dark_knight_fall_in_love/
https://www.mangago.zone/read-manga/couple_of_mirrors/
https://www.mangago.zone/read-manga/bead_master/
https://www.mangago.zone/read-manga/spinning_maiden_and_the_taishou_moon/
https://www.mangago.zone/read-manga/this_world_is_mine/
https://www.mangago.zone/read-manga/kanaria_wa_kiraboshi_no_yume_wo_miru/
https://www.mangago.zone/read-manga/akuyaku_reijou_no_o_yome_sama/
https://www.mangago.zone/read-manga/ryuu_to_ryuu_no_kekkon/
https://www.mangago.zone/read-manga/hitokiri_shoujo_koushaku_reijou_no_goei_ni_naru/
https://www.mangago.zone/read-manga/muryoku_seijo_to_munou_oujo/
https://www.mangago.zone/read-manga/sherbet_above_the_sea_of_fog/
https://www.mangago.zone/read-manga/heimin_no_watashi_desu_ga_koushaku_reijou_sama_o_taburakashite_ikiteimasu/
https://www.mangago.zone/read-manga/is_it_normal_to_raise_a_yandere_heroine_as_a_villainess/
https://www.mangago.zone/read-manga/dang_e_yi_yu_dao_bing_jiao/
https://www.mangago.zone/read-manga/kiraware_majo_reijou_to_dansou_ouji_no_kon_yaku/
https://www.mangago.zone/read-manga/the_princess_of_sylph/
https://www.mangago.zone/read-manga/please_bully_me_miss_villainess/
https://www.mangago.zone/read-manga/yukashi_yuusha_no_fukushuutan/
https://www.mangago.zone/read-manga/i_favor_the_villainess/
https://www.mangago.zone/read-manga/the_magical_revolution_of_the_reincarnated_princess_and_the_genius_young_lady/
https://www.mangago.zone/read-manga/do_you_think_someone_like_you_could_defeat_the_demon_lord/
https://www.mangago.zone/read-manga/gal_maid_villainess_only_milady_s_happy_end_will_win/
https://www.mangago.zone/read-manga/inari_no_kekkon/ (age gap)
https://www.mangago.zone/read-manga/the_fed_up_office_lady_wants_to_serve_the_villainess/ (age gap)
https://www.mangago.zone/read-manga/lady_black_is_depressed/ (non-con in chapters 14&15)
https://www.mangago.zone/read-manga/unnie_i_like_you/ (reincarnation trope so it combines modern (current life) + historical (past life) settings)
https://www.mangago.zone/read-manga/the_fox_is_getting_married/ (short story)
https://www.mangago.zone/read-manga/the_villainess_and_the_woman_who_would_do_anything_for_the_sake_of_love/ (short story)
https://www.mangago.zone/read-manga/will_we_live_happily_ever_after/ (one-shot)
https://www.mangago.zone/read-manga/shiroi_heya_no_futari/ (one-shot)
https://www.mangago.zone/read-manga/i_m_not_cut_out_to_be_a_princess_so_i_ll_elope_with_the_villainess/ (one-shot)
yuri/josei set in ancient china? or yuri set in whatever that vaguely victorian time period is?