Using Global Quick Actions in the Salesforce Mobile App

Follow the steps below to configure the Salesforce mobile app to display actions in the action bar.

1. Click Setup | Object Manager | target object | Page Layouts.
2. Select the page layout to edit.
3. Select Mobile & Lightning Actions.
4. Drag and drop the target global quick action into the Salesforce Mobile and Lightning Experience Actions section, and Save the page layout.

If dynamic actions are enabled and configured, the page layout settings are overridden by the settings in the Lightning Application Builder.

To enable dynamic actions for standard objects, go to Setup, enter "Mobile" in the Quick Find box, select "Salesforce Mobile App", and enable "Dynamic Actions on Mobile". After enabling, customize the page using the following steps:

1. Click Setup | Lightning App Builder.
2. Edit an existing record page or click New to create one.
3. Add or select the "Highlights Panel" component on the object record page.
4. Click "Upgrade Now" in the "Highlights Panel" component property pane and follow the migration assistant steps.
5. Click Add Action in the property pane and select an action from the Action window.
6. Click Done to save the changes.

Reference: Create Dynamic Actions in Lightning App Builder