Write a multi-page book with colours and styles, and get the /give command for it, in the right syntax for your version: item components on 1.21.5, on 1.20.5, or the old NBT tag before that.
Server Rules, by Staff
Colours and styles
2 pages
Garry's Mod
Minecraft/give @p written_book[written_book_content={title:"Server Rules",author:"Staff",pages:[["",{text:"Server Rules\n\n",color:"gold",bold:true},{text:"Read this before you build.\n\n",color:"black"},{text:"Griefing is a ban.",color:"dark_gray"}],["",{text:"Claim your land with ",color:"black"},{text:"/claim",color:"dark_gray"},{text:".\n\nAsk staff in chat.",color:"black"}]]}] 1