Animation: Mixamo Rig : Changing between animations in Blender

Download the Mixamo Blender Add On from: Mixamo Rig
Edit Preferences : Add Ons : Install and select the zip file you downloaded above.

In the Layout viewport you can see the options/properties of the Mixamo Add On . Click on the < icon on the righthand side

It shows the all the options. There is a Mixamo Tab:

Prepare another animation.

Go to Mixamo and search for the 'Standard Walk' animation.
Download

And now select <WITHOUT SKIN :

In Blender : File -> Import -> FBX and download the FBX file. Notice the smaller size that the file has ! It has only bone information

Select G from the keyboard and then type X and move the mouse to the left.

In Object Mode
Select the X-Pose Rig from the 'Armature' model

Click on Create Control Rig button

Keep the defaults and click [OK]
The rig gets altered:

Click on the eye dropper in the Source Skeleton

Point the eyedropper to the walk animation armature

Click on the Apply Animation to Control Rig button

Click on the play button for the animation (or press spacebar )

You can repeat this with all the mixamo animations.