You can buy the battlepass with the tokens earned in the battlepass.
1. You have to purchase the battle pass once as the tokens are not part of the "free" rewards.
2. You have to complete ALL tiers of the battlepass as the last 200 needed for 1100 is in the "prestige" tier.
3. The skins are somewhat cool BUT the battepass contains tons of "trash", icons, emblems, etc etc, **bleep** that you will never see and wont be thought of as cool because... well you bought it... compare the "phanthom dogtag" to having "120 counter sniper dogtags", one is cool the other is a whale trying to flex money.
TLDR: The battlepass is worthless if you play Battlefield 6, but can give you semi usefull things if you are f2p on BR and need better "skins" = "weapon kits". Akin to how buying bundles in Warzone let you skip the grind and equip actual good weapons.
It's a cashgrab and if too many people buy the battlepass the EA overlords might KILL BF6 with balance changes focused on BR instead of conquest/rush/squadDM.