connect asus router to wifi to get wider coverage

I have AT+T 5268AC router with my fiber service.  I know you don't support other party hardware so I am aware of that before submitting this question.

I have an ASUS RT-AC5300 wifi router which gives me extended coverage which is quite a bit more than AT+T 5268AC.

If I want to utilize the extended range of the ASUS, do I need to put the 5268AC in 'bridge mode' which I believe I have currently?

Or do I just need to keep the 5268AC in standard mode with my network name & password and just connect the ASUS with the same network name & password setup to get the extra range I'm trying to get?  (Probably just set the ASUS as an AccessPoint in that scenario).

Will this create any potential conflicts that you are aware of or can advise about?

Thanks for any guidance.