You can't expect everyone to get along in a server with hundreds of active players. Here's all the steps you can take if you're having issues with a player, and what to do if you have been blocked.
Blocking Someone In Minecraft
You can ignore players with the command /ignore. This will stop the player from sending you direct messages and teleport requests. This will also prevent you from seeing their messages in global chat.
You can use the command /pl3xmap hide to hide your location on the dynamic map.
You can ban a player from your claim with the command /gpflags setclaimflag noenterplayer.
Blocking Someone On Discord
You can block a player by right clicking the player's name and selecting the block option. This will prevent you from recieving direct messages from the player and will hide their messages in any mutual servers.
In a voice chat, you can right click on a player and turn their user volume down to 0%.
You can also report the player to Discord at https://dis.gd/report.
Reporting to Piglin
If you have taken all of the appropriate steps and the user continues to harass you, create a ticket on our Discord server explaining what happened. Screenshots, audio recordings, and other forms of evidence will help. You can recover logs from ingame chat using the steps provided here. Show that you have asked the player multiple times to stop communicating with you and that they continued through that. Also explain what they said and how their actions breaks Piglin's rules.
Be nice to others. Players typically block you if you've said or done something to hurt them. If this has happened, you should respect their wishes and stop trying to get in contact with them. Trying to communicate with someone to ask them why they blocked you typically only worsens the problem and could put you in a deeper hole. If you just let it be, the player may eventually realize that they have nothing to gain from blocking you and will eventually unblock you.