
When regular text boxes don’t do the trick it’s time to call WordArt!
Go to Insert > WordArt. Write your text and hit enter. Change the font to one you like and set border line to transparent.
Now go to Fill Color, click on Gradient and select Custom. We are going to create three different effects: Silver, Gold and Rose Gold.
How to Create a Silver Text Effect in Google Slides

To accomplish the silver effect, I’ve added four gradient stops on top of the default two.
To edit each gradient stop, click on each and click select gradient stop color, choose CUSTOM.
Here are the HEX color codes I’ve used from left to right: #ccccccff #f3f3f3ff #666666ff #434343ff #b7b7b7ff #f3f3f3ff
Once you are done, click OK.
How to Create a Gold Text Effect in Google Slides

Repeat the steps above (I’ve also used 6 gradients stops for this one). And use the following HEX color codes from left to right: #da9c10ff #ffda4bff #3d2101ff #9b6c14ff #c99939ff #f4c45eff
Once you are done, click OK.
How to Create a Rose Gold Text Effect in Google Slides

Yep, again you’ll have to repeat the steps above, add 4 gradient stops on top of the two that are given. And here you have the HEX color codes that I’ve used from left to right: #fefefeff #e1aca6ff #f4ccccff #5c2926ff #d48681ff #f7e1dfff
Click OK.
TIP: You can also add these effects to Shapes!
You can check the Roskilde theme that has little touches of gold.