This is how you can enable Gallery Labs.

[saadiMuhammad]

Step 1: Go to Settings and scroll down to About Gallery

Step 2: Open About Gallery and Tap 10 times on version number

That's how you will unlock the lab for Gallery 

[Saadi121]

Go on Gallery then settings then about Gallery then click 3 times or 4 times on his version it's enabled

[Saadi121]

Give me one favour please

[Saadi121]

Click on 3 dots on right and accept it as a solution please

[FarhanMehar]

Wao amazing. What's the importance of gallery lab?

[saadiMuhammad]

Nothing much just a few experimental features which might helpful.