You can try GitHub - lexus2k/ssd1306: Driver for SSD1306, SSD1331, SSD1351, IL9163, ILI9341, ST7735, PCD8544, Nokia 5110 displays running on Arduino/ESP32/Linux (Rasperry) platforms library and check draw_text sketch with your Attiny85: it uses less than 3KiB on Attiny85.
If to avoid using of ssd1306_printFixedN() function and use only ssd1306_printFixed(), sketch needs only 2KiB with the built-in font 6x8.