As shown below, Discord only allows for 50 custom emojis per server (unless you’re a Nitro member) and the upload requirements are as follows: Accepted file types: JPEG, PNG, GIF.

If you want more emoji slots, you'll need to have users with Discord Nitro accounts on the server to "boost'' the available slots. If enough users boost your server, you can add up to 250 custom ...

However, if you want to mute due to disruptive behavior, add a Discord bot to your Discord server. This way, you can issue mutes (and bans) by inputting the appropriate bot commands.

The perks for the Discord Nitro Server Boost Levels are as follows, courtesy of the Discord Blog: Level 1 Perks: +50 Emoji Slots (for a total of 100 emojis) 128 Kbps Audio Quality Custom Splash ...