One thing you can do is if you don’t have membership website then make it such that wp-admin/wp-login can be open through your IP address and block all other IP address. But make sure that you don’t have membership website (No other subscribers/publishers that can login. Only you are the person to log in.)
The other thing you can do is use “CDN” like cloudflare which will filter the IPs before reaching to your server. This make your site fast as well.
Hope this helps.