To manage tmux sessions, I like to use tmuxp. It works by having pre-defined sessions in ~/.config/tmuxp which looks like this:

session_name: cool-app
start_directory: ~/projects/cool-app
windows:
- window_name: backend
  start_directory: backend
- window_name: frontend
  start_directory: frontend

In case the name of the file is cool-app.yaml, you can open the sessions with tmuxp load cool-app --yes.