How do I sync apps on my IPad and Iphone

Do you know if the app developer offers an iPad version of the app?

Go to Settings > App Store > Tap the little circle in the top right with your photo in it > Tap Purchased > Tap My Purchases > If this app is available for iPad, it will be in the list with a cloud icon. Tap the cloud icon and it will download to your iPad.

Here is a support article with more info: https://support.apple.com/en-us/HT202180

The App Store will have a record of any purchases you make, so if you go into it on another device, you can re-download any items.

Go into Settings > iTunes & App Store --under Automatic Downloads, make sure Apps is turned on

Are you using the same Apple ID on both iPhone and iPad?

OK. So being specific, what is the issue you are experiencing? Sync apps doesn't give us much to go on.