Samsung Galaxy S10 5G - Add a Speed Dial

From a Home screen, tap the Phone icon (lower-left).
If unavailable, swipe up or down from the center of the display then tap Phone .
From the Contacts tab (lower-right), tap the Menu icon (upper-right).
Tap Speed dial numbers.
From the 'Name or number' field, enter the name of number of the desired contact.
As the name or number is entered, a list of matching contacts may appear and can be selected at any time.
To change the speed dial number, tap the Dropdown menu icon then select the desired number (e.g., 3, 4, 10, etc.).