OneNote's Tags functionality is imported in Trilium as Icons using the default icon pack or emojis (if there is no suitable replacement).

Decorative tags

These remain formatted as paragraphs, with the glyph prepended to the text. A paragraph can carry several tags at once, in which case their glyphs stack.

OneNote tag data-tag Imported as Searchable as
Important important star
Critical critical error-circle
Question question help-circle
Highlight highlight highlight
Definition remember-for-later pin
Remember for later remember-for-later pin
Remember for blog remember-for-blog edit
Idea idea bulb
Password password key
Contact contact user
Address address home
Phone number phone-number phone
Web site to visit web-site-to-visit globe
Source for article source-for-article news
Send in email send-in-email envelope
Movie to see movie-to-see movie
Book to read book-to-read book
Music to listen to music-to-listen-to music
Project A project-a 🅰️ 🅰️
Project B project-b 🅱️ 🅱️

Check box tags

These become To-do Lists, with the glyph inside the item with the tick state preserved:

OneNote tag data-tag Imported as Searchable as
To Do to-do (none) —
To Do priority 1 to-do-priority-1 1️⃣ 1️⃣
To Do priority 2 to-do-priority-2 2️⃣ 2️⃣
Discuss with Person A discuss-with-person-a message-rounded
Discuss with Person B discuss-with-person-b message-rounded
Discuss with manager discuss-with-manager conversation
Schedule meeting schedule-meeting calendar
Call back call-back phone-call
Client request client-request clipboard