Static assets rarely change, so tell the browser to keep them. A regex location matching common extensions does it.

location ~* \.(?:css|js|woff2?|ttf|otf|eot|ico|gif|png|jpe?g|webp|avif|svg|mp4)$ {
    expires 30d;
    add_header Cache-Control "public";
    access_log off;             # optional: stop logging every asset hit
    try_files $uri =404;
}

For content-hashed filenames (e.g. app.4f3a1c.js from a bundler) you can cache forever, because a change ships a new filename:

location ~* \.(?:css|js|woff2)$ {
    expires 1y;
    add_header Cache-Control "public, immutable";
}

Notes:

expires sets both the Expires and Cache-Control: max-age headers. expires 1y; = max-age=31536000.
immutable tells modern browsers not to even revalidate during the lifetime — no conditional request on reload. Only safe for filenames that change when content changes.
~* is a case-insensitive regex match. Regex locations are checked before plain prefixes, so this catches assets regardless of which folder they’re in. If you keep all assets under one path, a prefix location /assets/ { … } is cheaper than a regex.
For HTML, do the opposite — short or no cache (Cache-Control "no-cache"), so content updates show up immediately.

Check it landed:

curl -sI https://example.com/app.4f3a1c.js | grep -i cache-control
# cache-control: public, immutable

Cache static assets in the browser