
Hi Kumar,
PowerPoint Designer isn't exposed as its own tab anymore. You'll find it on the Design ribbon as the "Design Ideas" button on the far right. If you don't see that button you're most likely running a perpetual-license copy (2019/2021) or you haven't enabled Office's cloud features.
First, switch to the Design tab and look for "Design Ideas". If it's missing, go to File > Options > General and scroll down to the PowerPoint Designer section. Make sure "Automatically show suggestions" is checked. Then open Privacy Settings and enable connected experiences (so PowerPoint can fetch designs from the cloud). Finally, confirm you're signed in with an active Microsoft 365 account and restart PowerPoint. After that the Design Ideas button should appear.