You can set it to openvpn's --route-up and --down scripts. 1. https://openvpn.net/community-resources/reference-manual-for-openvpn-2-4/， 2. https://github.com/17mon/china_ip_list

macos_route_table_quick_manipulate.lua

#!/usr/local/bin/luajit

local interface = "Wi-Fi"
local action = arg[1]
assert(action == "add" or action == "del" or action == "get")

local cmd = ""
if action == "get" then
    cmd = "/usr/bin/sudo /usr/sbin/networksetup -getadditionalroutes " .. interface
    print(cmd)
    os.execute(cmd)
    os.exit(0)
elseif action == "del" then
    local gateway = assert(io.popen("/sbin/route -n get default"):read("*a"):match("gateway:%s+([%S]*)"))
    cmd = "/usr/bin/sudo /usr/sbin/networksetup -setadditionalroutes " .. interface
    print(cmd)
    os.execute(cmd)
    for i = 0, 50 do
        if not io.popen("/usr/bin/sudo /sbin/route -q -n flush -inet"):read() then
            break
        end
    end
    cmd = "/usr/bin/sudo /sbin/route -q add -net 0.0.0.0 " .. gateway

    print(cmd)
    os.execute(cmd)
    os.exit(0)
end

local gateway = assert(os.getenv("route_net_gateway"))
local max_line = arg[2] and assert(tonumber(arg[2]))
local mask_table = {
    [0] = "0.0.0.0",
    [1] = "128.0.0.0",
    [2] = "192.0.0.0",
    [3] = "224.0.0.0",
    [4] = "240.0.0.0",
    [5] = "248.0.0.0",
    [6] = "252.0.0.0",
    [7] = "254.0.0.0",
    [8] = "255.0.0.0",
    [9] = "255.128.0.0",
    [10] = "255.192.0.0",
    [11] = "255.224.0.0",
    [12] = "255.240.0.0",
    [13] = "255.248.0.0",
    [14] = "255.252.0.0",
    [15] = "255.254.0.0",
    [16] = "255.255.0.0",
    [17] = "255.255.128.0",
    [18] = "255.255.192.0",
    [19] = "255.255.224.0",
    [20] = "255.255.240.0",
    [21] = "255.255.248.0",
    [22] = "255.255.252.0",
    [23] = "255.255.254.0",
    [24] = "255.255.255.0",
    [25] = "255.255.255.128",
    [26] = "255.255.255.192",
    [27] = "255.255.255.224",
    [28] = "255.255.255.240",
    [29] = "255.255.255.248",
    [30] = "255.255.255.252",
    [31] = "255.255.255.254",
    [32] = "255.255.255.255",
}

-- local txt_file = arg[0]:gsub("/[^/]*$", "/china_ip_list.txt")
local txt_file = "./china_ip_list.txt"
local fh = assert(io.open(txt_file))
local result = {}
local line_num = 0
for line in fh:lines() do
    if line:len() > 0 then
        local ip, mask = line:match("^(%d+%.%d+%.%d+%.%d+)/(%d+)")
        mask = assert(tonumber(mask))
        assert(mask >= 0 and mask <= 32)
        mask = mask_table[mask]
        local record = ip .. " " .. mask .. " " .. gateway

        -- print(line, record)
        table.insert(result, record)

        line_num = line_num + 1
        if max_line and line_num >= max_line then
            break
        end
    end
end
os.execute("/usr/bin/sudo /usr/sbin/networksetup -setadditionalroutes " .. interface .. " " .. table.concat(result, " "))
fh:close()