Allow access from CloudFlare IP range only.

cloudflare-apache.conf

Source: https://stackoverflow.com/questions/65448093/allowing-only-cloudflare-i-p-range-through-htaccess-giving-403-error

#path to your website
<Directory "path/to/public_html/or/var/www/html">
    #ipv4
    Require ip 173.245.48.0/20
    Require ip 103.21.244.0/22
    Require ip 103.22.200.0/22
    Require ip 103.31.4.0/22
    Require ip 141.101.64.0/18
    Require ip 108.162.192.0/18
    Require ip 190.93.240.0/20
    Require ip 188.114.96.0/20
    Require ip 197.234.240.0/22
    Require ip 198.41.128.0/17
    Require ip 162.158.0.0/15
    Require ip 104.16.0.0/12
    Require ip 172.64.0.0/13
    Require ip 131.0.72.0/22
    #ipv6
    Require ip 2400:cb00::/32
    Require ip 2606:4700::/32
    Require ip 2803:f800::/32
    Require ip 2405:b500::/32
    Require ip 2405:8100::/32
    Require ip 2a06:98c0::/29
    Require ip 2c0f:f248::/32
</Directory>