How does location processing work in Nginx?

Question

Nginx

server {
  listen 81;
  root  /usr/share/nginx/html/app;
  
  location / {
    try_files $uri $uri/ /index.html;
  }

  location = /admin {
    alias /usr/share/nginx/html/app2;
  }
}

How to deal with the processing of locaiton / admin?
I would like it to open along the /admin path, but it only works if there is a slash at the end of the uri.