Oracle 18c

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

with start_params as (
    select
        to_date('01/01/2020', 'MM/DD/YYYY') as start_date,
        60 numdays
    from dual
),
colors as (
    select to_date('1/28/2020 09:29', 'MM/DD/YYYY HH24:MI') as color_date, 'red' as color,  1 color_count from dual union
    select to_date('2/3/2020 07:04', 'MM/DD/YYYY HH24:MI') as color_date,  'red' as color,  5 color_count from dual union
    select to_date('2/6/2020 12:11', 'MM/DD/YYYY HH24:MI') as color_date,  'red' as color,  11 color_count from dual union
    select to_date('2/11/2020 17:15', 'MM/DD/YYYY HH24:MI') as color_date,  'red' as color,  4 color_count from dual union
    select to_date('2/15/2020 03:46', 'MM/DD/YYYY HH24:MI') as color_date,  'red' as color,  6 color_count from dual union
    select to_date('1/16/2020 14:52', 'MM/DD/YYYY HH24:MI') as color_date, 'blue' as color, 7 color_count from dual union
    select to_date('1/19/2020 22:30', 'MM/DD/YYYY HH24:MI') as color_date, 'blue' as color, 32 color_count from dual union
    select to_date('1/23/2020 05:17', 'MM/DD/YYYY HH24:MI') as color_date, 'blue' as color, 16 color_count from dual union
    select to_date('1/28/2020 18:35', 'MM/DD/YYYY HH24:MI') as color_date, 'blue' as color, 24 color_count from dual union
    select to_date('1/31/2020 15:38', 'MM/DD/YYYY HH24:MI') as color_date, 'blue' as color, 41 color_count from dual union
    select to_date('2/2/2020 16:01', 'MM/DD/YYYY HH24:MI') as color_date,  'blue' as color, 11 color_count from dual
),
upd_colors as (
    select
        (select start_date from start_params) color_date,
        color,
        min(color_count) keep(dense_rank first order by color_date) color_count
    from colors
    group by color
    union all
    select trunc(color_date), color, color_count from colors
),
dates as (
    select dat, color
    from (
        select start_date + numtodsinterval(level-1, 'DAY') dat
        from start_params connect by level <= numdays
    ), (select distinct color from colors)
)
select d.dat, d.color,
    nvl(c.color_count, lag(c.color_count ignore nulls) over (partition by d.color order by d.dat)) color_count
from dates d, upd_colors c
where c.color_date(+) = d.dat
  and c.color(+) = d.color
order by color, dat

DAT	COLOR	COLOR_COUNT
01-JAN-20	blue	7
02-JAN-20	blue	7
03-JAN-20	blue	7
04-JAN-20	blue	7
05-JAN-20	blue	7
06-JAN-20	blue	7
07-JAN-20	blue	7
08-JAN-20	blue	7
09-JAN-20	blue	7
10-JAN-20	blue	7
11-JAN-20	blue	7
12-JAN-20	blue	7
13-JAN-20	blue	7
14-JAN-20	blue	7
15-JAN-20	blue	7
16-JAN-20	blue	7
17-JAN-20	blue	7
18-JAN-20	blue	7
19-JAN-20	blue	32
20-JAN-20	blue	32
21-JAN-20	blue	32
22-JAN-20	blue	32
23-JAN-20	blue	16
24-JAN-20	blue	16
25-JAN-20	blue	16
26-JAN-20	blue	16
27-JAN-20	blue	16
28-JAN-20	blue	24
29-JAN-20	blue	24
30-JAN-20	blue	24
31-JAN-20	blue	41
01-FEB-20	blue	41
02-FEB-20	blue	11
03-FEB-20	blue	11
04-FEB-20	blue	11
05-FEB-20	blue	11
06-FEB-20	blue	11
07-FEB-20	blue	11
08-FEB-20	blue	11
09-FEB-20	blue	11
10-FEB-20	blue	11
11-FEB-20	blue	11
12-FEB-20	blue	11
13-FEB-20	blue	11
14-FEB-20	blue	11
15-FEB-20	blue	11
16-FEB-20	blue	11
17-FEB-20	blue	11
18-FEB-20	blue	11
19-FEB-20	blue	11
20-FEB-20	blue	11
21-FEB-20	blue	11
22-FEB-20	blue	11
23-FEB-20	blue	11
24-FEB-20	blue	11
25-FEB-20	blue	11
26-FEB-20	blue	11
27-FEB-20	blue	11
28-FEB-20	blue	11
29-FEB-20	blue	11
01-JAN-20	red	1
02-JAN-20	red	1
03-JAN-20	red	1
04-JAN-20	red	1
05-JAN-20	red	1
06-JAN-20	red	1
07-JAN-20	red	1
08-JAN-20	red	1
09-JAN-20	red	1
10-JAN-20	red	1
11-JAN-20	red	1
12-JAN-20	red	1
13-JAN-20	red	1
14-JAN-20	red	1
15-JAN-20	red	1
16-JAN-20	red	1
17-JAN-20	red	1
18-JAN-20	red	1
19-JAN-20	red	1
20-JAN-20	red	1
21-JAN-20	red	1
22-JAN-20	red	1
23-JAN-20	red	1
24-JAN-20	red	1
25-JAN-20	red	1
26-JAN-20	red	1
27-JAN-20	red	1
28-JAN-20	red	1
29-JAN-20	red	1
30-JAN-20	red	1
31-JAN-20	red	1
01-FEB-20	red	1
02-FEB-20	red	1
03-FEB-20	red	5
04-FEB-20	red	5
05-FEB-20	red	5
06-FEB-20	red	11
07-FEB-20	red	11
08-FEB-20	red	11
09-FEB-20	red	11
10-FEB-20	red	11
11-FEB-20	red	4
12-FEB-20	red	4
13-FEB-20	red	4
14-FEB-20	red	4
15-FEB-20	red	6
16-FEB-20	red	6
17-FEB-20	red	6
18-FEB-20	red	6
19-FEB-20	red	6
20-FEB-20	red	6
21-FEB-20	red	6
22-FEB-20	red	6
23-FEB-20	red	6
24-FEB-20	red	6
25-FEB-20	red	6
26-FEB-20	red	6
27-FEB-20	red	6
28-FEB-20	red	6
29-FEB-20	red	6