Instead Of Levelling Up from 100...
How about adding player tiers? Every 500 or 1000 levels, players go up a tier and receive a legendary item of their choice. Badges could have some fancy frames, showing the tiers with stars or with roman numbers, and the levels with smaller digits (so that "999" doesn't spill).
Level up rewards can still be limited, like introducing a limited number of packs every season or year. Each pack would be obtained after 4-5 levels. In the main screen, there could be a pack counter, displaying the number of packs obtained & unopened / remaining number of packs to be unlocked.
It just feels weird to me to start going up from level 100, although I'm over 400 on various trackers. It's not like I stopped playing when reaching the cap, I actually gained a lot of experience in the months after. Besides, there's hardly any better way to show your true game wisdom than a level badge and many of us miss it in Apex because of the cap.Also, a level 100 player with 20.000+ kills will likely be reported as a cheater by many, so most veterans will probably ignore the badges.