To level up fast in Battlefield, especially Battlefield 6, focus on playing the objective such as capturing points, defending positions, and completing class-specific roles effectively, like reviving teammates as Support or repairing vehicles as Engineer. Using XP boost tokens during gameplay doubles the points earned, speeding progression. Another fast method is farming XP in custom Portal mode with bots, where you can repeatedly capture points and kill bots efficiently, gaining thousands of XP quickly. Also, complete daily and weekly challenges consistently for significant XP bonuses. Using your class role correctly and stacking in-game bonuses will further accelerate leveling.

Key tips include:

• Play objective modes and fulfill your class duties.
• Use XP boost tokens strategically to maximize XP gains.
• Farm kills and objectives in custom bot matches for rapid weapon and career XP.
• Complete daily/weekly challenges for additional XP.
• Choose Support class for fast XP through revives and ammo drops in chokepoint maps like Breakthrough.

This approach will help you gain weapon attachments and unlock key gadgets faster as you progress your career rank and weapons more efficiently than just casual play.